Electronic apparatus and accessory

ABSTRACT

An electronic apparatus detachably attached to an accessory via an accessory shoe includes contacts electrically connectable to the accessory via the accessory shoe and arranged in a row. The contacts include a first signal contact used to transmit a data signal in a communication between the electronic apparatus and accessory, a second signal contact used to transmit a clock signal in synchronization with the data signal in the communication, and a third signal contact used to receive a communication request signal from the accessory. The first and second signal contacts are arranged next to each other. The third signal contact is disposed on an opposite side of the second signal contact with respect to the first signal contact. A transmission of the data signal via the first signal contact is executed in response to a reception of the communication request signal via the third signal contact.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/JP2021/014278, filed on Apr. 2, 2021, which claims the benefitof Japanese Patent Applications Nos. 2020-070625, filed on Apr. 9, 2020,2020-070626, filed on Apr. 9, 2020, 2020-070627, filed on Apr. 9, 2020,and 2021-060103, filed on Mar. 31, 2021 each of which are herebyincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an electronic apparatus and anaccessory, each of which has a contact used for a communication, a powersupply, and the like.

Description of the Related Art

An accessory such as a strobe device is attached to an accessory shoeprovided to an electronic apparatus, such as a camera. The accessoryshoe is provided with a plurality of contacts (terminals) for supplyingthe power to the accessory and for communicating with the accessory. Ifa signal connected to a certain contact receives noises from a signalconnected to an adjacent contact during the communication between theelectronic apparatus and the accessory, it may cause a malfunction ofthe electronic apparatus or the accessory.

Japanese Patent Laid-Open No. 2013-34172 discloses a camera and anaccessory, in which a contact for notifying the camera of an activatablestate of the accessory is disposed next to one of contacts to which adata signal as a communication signal is connected, and a groundedcontact is disposed next to the other of the contacts of the datasignal.

However, Japanese Patent Laid-Open No. 2013-34172 is silent about acontact arrangement for avoiding interference with a communicationsignal, which is caused by a change in another signal.

SUMMARY OF THE INVENTION

The present invention provides an electronic apparatus and an accessory,each of which can suppress interference with a communication signal,which is caused by a change in another signal.

An electronic apparatus according to another aspect of the presentinvention detachably attached to an accessory via an accessory shoeincludes a plurality of contacts electrically connectable to theaccessory via the accessory shoe and arranged in a row. The plurality ofcontacts include a first signal contact used to transmit a data signalin a communication between the electronic apparatus and the accessory, asecond signal contact used to transmit a clock signal in synchronizationwith the data signal in the communication, and a third signal contactused to receive a communication request signal from the accessory. Thefirst signal contact and the second signal contact are arranged next toeach other. The third signal contact is disposed on an opposite side ofthe second signal contact with respect to the first signal contact. Atransmission of the data signal via the first signal contact is executedin response to a reception of the communication request signal via thethird signal contact.

An accessory according to another aspect of the present inventiondetachably attached to an electronic apparatus via an accessory shoeincludes a plurality of contacts electrically connectable to theaccessory shoe of the electronic apparatus and arranged in a row. Theplurality of contacts include a first signal contact used to transmit adata signal in a communication between the electronic apparatus and theaccessory, a second signal contact used to receive a clock signal insynchronization with the data signal in the communication, and a thirdsignal contact used to transmit a communication request signal to theelectronic apparatus. The first signal contact and the second signalcontact are arranged next to each other. The third signal contact isdisposed on an opposite side of the second signal contact with respectto the first signal contact. A reception of the data signal via thefirst signal contact is executed in response to a transmission of thecommunication request signal via the third signal contact.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates configurations of a camera and an accessory accordingto one embodiment of the present invention.

FIGS. 2A, 2B, and 2C illustrate an example of the camera to which theaccessory is attached and their contact arrangements according to theembodiment.

FIGS. 3A and 3B illustrate how an external force is applied to theaccessory attached to the camera according to the embodiment.

FIG. 4A is a diagram illustrating a configuration for determining aconnection state of a grounded contact according to the embodiment.

FIG. 4B is a flowchart showing processing executed by the cameraaccording to the embodiment.

FIGS. 5A and 5B are flowcharts showing processing executed by the cameraaccording to the embodiment.

FIGS. 6A, 6B, and 6C are timing charts illustrating a signal change whena contact adjacent to a power supply contact is short-circuitedaccording to the embodiment.

FIG. 7 illustrates an assignment example of a functional signal to atype of the accessory according to the embodiment.

FIGS. 8A, 8B, and 8C illustrate a connection destination configurationof the functional signal according to the embodiment.

FIG. 9 illustrates a configuration example of the camera and theaccessory according to the embodiment.

FIG. 10 illustrates another configuration example of the camera andaccessories according to the embodiment.

FIG. 11 illustrates still another configuration example of the cameraand accessories according to the embodiment.

FIG. 12 illustrates a configuration example of the accessory accordingto the embodiment.

FIG. 13 illustrates a configuration example of the camera, theaccessory, and an intermediate accessory according to the embodiment.

FIG. 14 illustrates another configuration example of the camera, theaccessory, and the intermediate accessory according to the embodiment.

FIGS. 15A and 15B are timing charts when the accessory is a strobedevice according to the embodiment.

FIGS. 16A, 16B, and 16C are perspective views of the camera and anexternal flash unit as the accessory according to an embodiment.

FIGS. 17A and 17B are an exploded view and a perspective view of anaccessory shoe according to the embodiment.

FIGS. 18A, 18B, and 18C illustrate a structure of an engagement memberand a connection terminal connector of an accessory shoe according tothe embodiment.

FIGS. 19A and 19B are a perspective view and a sectional view of theexternal flash unit according to the embodiment.

FIGS. 20A, 20B, and 20C are a perspective view and a front viewillustrating an internal structure of a camera connector according tothe embodiment.

FIGS. 21A and 21B are a top view and a sectional view of a cameraconnector according to the embodiment.

FIGS. 22A and 22B are a perspective view and a sectional view of anexternal flash unit according to a variation.

FIGS. 23A and 23B are a perspective view and a front view illustratingthe internal structure of the connector according to the variation.

FIG. 24 is a front view of the accessory shoe according to theembodiment.

FIG. 25 is a partially enlarged view of a connection plug according tothe embodiment.

FIG. 26 is a front sectional view illustrating a state in which a cameraconnector is attached to an accessory shoe according to the embodiment.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the accompanying drawings, a description will be givenof embodiments according to the present invention.

FIG. 1 illustrates an electrical configuration of a camera 100 as anelectronic apparatus according to one embodiment of the presentinvention and an accessory 200 detachably attached to the camera 100. Inthe camera 100 and the accessory 200, a plurality of contacts(terminals) TC01 to TC21 of a camera connector 141 provided in thecamera 100 and a plurality of contacts TA01 to TA21 of an accessoryconnector 211 provided in the accessory 200 are connected to each otherin a one-to-one correspondence, respectively and thereby they areelectrically connected with each other.

The camera 100 is supplied with the electric power from a battery 111.The battery 111 is attachable to and detachable from the camera 100. Acamera control circuit 101 as a control means of the camera 100 is acircuit that controls the entire camera 100, and includes amicrocomputer having a built-in CPU or the like.

A system power supply circuit 112 is a circuit that generates a powersupply for supplying the power to each circuit in the camera 100, andincludes a DC/DC converter circuit, an LDO (Low Drop Out), a charge pumpcircuit, and the like. A voltage of 1.8V generated by the system powersupply circuit 112 is constantly supplied as a camera microcomputerpower supply VMCU_C from the battery 111 to the camera control circuit101. The camera control circuit 101 controls the system power supplycircuit 112 and thereby controls turning on and off of the power supplyto each circuit of the camera 100.

An optical lens 121 is attachable to and detachable from the camera 100.Light from an object incident through the optical lens 121 is imaged onan image sensor 122 including a CMOS sensor, a CCD sensor, or the like.The object image formed on the image sensor 122 is encoded into adigital imaging signal. An image processing circuit 123 performs imageprocessing such as noise reduction processing and white balanceprocessing for the digital imaging signal to generate image data, andconverts it into an image file, such as a JPEG format, in order torecord the image data in a recording memory 126. The image processingcircuit 123 generates from the image data VRAM image data for display ona display circuit 127.

A memory control circuit 124 controls a transmission and reception ofthe image data and other data generated by the image processing circuit123 and the like. A volatile memory 125 is a memory capable ofhigh-speed reading and writing such as DDR3 SDRAM, and is used for aworkspace or the like of the image processing performed by the imageprocessing circuit 123. The recording memory 126 is a readable andwritable recording medium such as an SD card or CFexpress card that isattachable to and detachable from the camera 100 via an unillustratedconnector. The display circuit 127 is a display located on the backsurface of the camera 100, and includes an LCD panel, an organic ELdisplay panel, and the like. A backlight circuit 128 adjusts thebrightness of the display circuit 127 by changing a light amount of thebacklight of the display circuit 127.

Each of an accessory-use power supply circuit A131 and an accessory-usepower supply circuit B132 as the power supply means is a voltageconversion circuit that converts the voltage supplied from the systempower supply circuit 112 into a predetermined voltage, and generates 3.3V as an accessory power supply VACC in this embodiment.

The accessory-use power supply circuit A131 is a power supply circuitincluding an LDO or the like and having a low self-consumption power.The accessory-use power supply circuit B132 is a circuit that includes aDC/DC converter circuit or the like and can flow a larger current thanthat of the accessory-use power supply circuit A131. Theself-consumption power of the accessory-use power supply circuit B132 islarger than that of the accessory-use power supply circuit A131.Therefore, when the load current is small, the accessory-use powersupply circuit A131 is more efficient than the accessory-use powersupply circuit B132, and when the load current is large, theaccessory-use power supply circuit B132 is more efficient than theaccessory-use power supply circuit A131. The camera control circuit 101controls turning on and off of the voltage outputs of the accessory-usepower supply circuits A131 and B132 according to the operating state ofthe accessory 200.

A protection circuit 133 as a protection means includes a current fuseelement, a poly-switching element, an electronic fuse circuit thatcombines a resistor, an amplifier, and a switching element, and thelike, and outputs an overcurrent detection signal DET_OVC when the powersupply current values from the accessory-use power supply circuits A131and B132 to the accessory 200 become excessive (abnormal) beyond apredetermined value. In this embodiment, the protection circuit 133includes an electronic fuse circuit, and notifies the camera controlcircuit 101 through the overcurrent detection signal DET_OVC when thecurrent of 1 A or higher flows. The overcurrent detection signal DET_OVCindicates the overcurrent through the Hi level.

A camera connector 141 is a connector for an electrical connection withthe accessory 200 via 21 contacts TC01 to TC21 arranged in a row. Thecontacts TC01 to TC21 are arranged in this order from one end to theother end in the arrangement direction thereof.

TC01 is connected to the ground (GND) and serves not only as a contactfor the reference potential (GND potential) but also as a contact forcontrolling the wiring impedance of differential signals D1N and D1Pdescribed below. TC01 corresponds to a third grounded contact.

The differential signal D1N connected to TC02 and the differentialsignal D1P connected to TC03 are paired differential data communicationsignals that perform a data communication, and connected to the cameracontrol circuit 101. TC02, TC03, TC07 to TC17, TC19, and TC20, whichwill be described later, are communication contacts.

TC04 as a first grounded contact is connected to GND and serves as areference potential contact between the camera 100 and the accessory200. TC04 is disposed outside TC05 described below in the contactarrangement direction.

The accessory power supply VACC generated by the accessory-use powersupply circuits A131 and B132 is connected to TC05 as the power supplycontact via the protection circuit 133.

An accessory attachment detection signal/ACC_DET is connected to TC06 asan attachment detection contact. The accessory attachment detectionsignal/ACC_DET is pulled up to the camera microcomputer power supplyVMCU_C via a resistor element Rp134 (10 kΩ). The camera control circuit101 can detect whether or not the accessory 200 is attached, by readingthe signal level of the accessory attachment detection signal/ACC_DET.If the accessory attachment detection signal/ACC_DET signal level(potential) is a Hi level (predetermined potential), the accessory 200is detected as being non-attached, and if it is a Lo level (GNDpotential as described later), the accessory 200 is detected as beingattached.

When the camera 100 is powered on and the signal level (potential) ofthe accessory attachment detection signal/ACC_DET changes from the Hilevel to the Lo level, various transmissions are performed between thecamera 100 and the accessory 200 via the contacts.

The camera control circuit 101 supplies the power to the accessory 200via TC05 as a power supply contact when the attachment state of theaccessory 200 is detected.

SCLK connected to TC07, MOSI connected to TC08, MISO connected to TC09,and CS connected to TC10 are signals used by the camera control circuit101 as a communication master to perform a SPI (Serial PeripheralInterface) communication. In this embodiment, the communication clockfrequency of the SPI communication is 1 MHz.

A communication request signal/WAKE for requesting a communication fromthe accessory 200 to the camera control circuit 101 is connected toTC11. The communication request signal/WAKE is pulled up to the cameramicrocomputer power supply VMCU_C via a resistor. The camera controlcircuit 101 can receive the communication request from the accessory 200by detecting a trailing edge of the communication request signal/WAKE.

SDA connected to TC12 and SCL connected to the TC13 are signals for thecamera control circuit 101 to act as a communication master and performan I2C (Inter-Integrated Circuit) communication. SDA and SCL are signalsfor an open drain communication (referred to as an open draincommunication hereinafter) pulled up to the camera microcomputer powersupply VMCU_C, and the communication frequency is 100 kbps in thisembodiment.

In the I2C communication, both the data transmission from the camera 100and the data transmission from the accessory 200 are performed via theSDA. When the SPI communication and the I2C communication are comparedwith each other, the I2C communication has a lower communication speedthan that of the SPI communication, and can achieve a lower powerconsumption. The SPI communication has a higher communication speed thanthe I2C communication, and is therefore suitable for a communication ofinformation having a large data amount. Therefore, in the communicationbetween the camera 100 and the accessory 200 according to thisembodiment, information having a large data amount is communicated inthe SPI communication, and information having a small data amount iscommunicated in the I2C communication. For example, data is firstcommunicated in the I2C communication, and a control is made so that theSPI communication is further executed when the SPI communication can beexecuted or the SPI communication needs to be executed based on thisdata.

An FNC1 signal connected to TC14 (synchronous contact), an FNC2 signalconnected to TC15, an FNC3 signal connected to TC16, and an FNC4 signalconnected to TC17 are signals that can change the function according tothe type of the attached accessory 200. For example, when the accessory200 is a microphone device, the signal communicated via TC 15 is anaudio data signal. When the accessory 200 is an illumination (strobe orflash) unit, the signal communicated via TC14 is a signal forcontrolling the light emission timing. Depending on the type of theattached accessory, a signal that realizes a different function may becommunicated via the same contact. For example, when the accessory 200is an accessory other than the illumination unit, a synchronizationsignal for controlling a timing different from the light emission timingmay be communicated via TC14. TC14 to TC17 correspond to functionalsignal contacts. A communication using at least one of the functionalsignal contacts is also referred to as a functional signalcommunication.

The functional signal communication can execute a communication at atiming that does not depend on the I2C communication or the SPIcommunication in parallel with the I2C communication and the SPIcommunication.

The type of the accessory, as used herein, means the above-mentionedmicrophone device, illumination unit, and the like. Accessories thatachieve the same purpose, such as illuminations with differentperformances, belong to the same type. Accessories that achievedifferent purposes, such as a microphone device and an illuminationunit, belong to different types.

The functional signal communication is executed based on the informationacquired by the I2C communication or the SPI communication.

TC18 as a second grounded contact (reference potential contact) is alsoconnected to GND, and is a contact that serves as a reference potentialbetween the camera 100 and the accessory 200, similar to TC04.

A differential signal D2N connected to TC19 (first differential signalcontact) and a differential signal D2P connected to TC20 (seconddifferential signal contact) are paired data communication signals thatperform a data communication and connected to the camera control circuit101. For example, the USB communication can be performed via TC19 andTC20.

TC21 is connected to GND and can be used not only as a contact for areference potential but also as a contact for controlling the wiringimpedance of the differential signals D2N and D2P. TC21 corresponds to afourth grounded contact.

The contacts TC01, TC04, TC06, TC18, and TC21 are connected, forexample, to a GND portion of a flexible substrate 158 illustrated inFIG. 17, which will be described later, and the GND portion of theflexible substrate 158 is fixed with a metallic member having a GNDlevel of the camera 100 by a screw 157 or the like. The metallic memberhaving the GND level includes, for example, an engagement member 151, anunillustrated base plate inside the camera 100, and the like.

This embodiment disposes the attachment detection contact TC06 to whichthe accessory attachment detection signal/ACC_DET is connected isarranged, next to the contact (first clock contact) TC07 that transmitsSCLK (first clock signal) as a clock signal. In general, a noise (clocknoise) due to the potential fluctuation of the clock signal istransmitted to a contact adjacent to the contact of the clock signal,which may cause a malfunction. In particular, in a configuration havinga large number of contacts and a short distance between contacts as inthis embodiment, the influence is more significant. Accordingly,disposing the attachment detection contact TC06 next to the SCLK contactTC07 can suppress the influence of the clock noise.

The accessory attachment detection signal/ACC_DET is pulled up beforethe accessory is attached, but is set to the GND potential after theaccessory is attached. On the other hand, the SCLK contact TC07 thattransmits the clock signal does not transmit the clock signal before theaccessory is attached, and thus the potential does not fluctuate. Thepotential fluctuates because the clock signal is transmitted only afterthe accessory is attached.

When the SCLK contact TC07 transmits the clock signal, the attachmentdetection contact TC06 is at the GND potential. Therefore, even if theattachment detection contact TC06 receives the clock noises, thepotential of the control circuit of the camera 100 or the accessory 200is less likely to fluctuate, so that the malfunction can be prevented.In addition, the clock noise can be restrained from transmitting to aposition distant farther than the attachment detection contact TC06. Asa result, since it is unnecessary to dispose the GND terminal, theinfluence of the clock noises can be suppressed without increasing thenumber of contacts.

SCL (second clock signal) as a clock signal is also transmitted to thecontact (second clock contact) TC13. However, the frequency of SCLKtransmitted to the SCLK contact TC07 is higher than that of SCL, and theSCLK contact TC07 generates more clock noises than the SCL contact TC13.Therefore, disposing the attachment detection contact TC06 next to theSCLK contact TC07 rather than next to the SCL contact TC13 can provide agreater effect of preventing the malfunction due to the clock noises.

In addition to the difference in frequency, SCL transmitted by the SCLcontact TC13 is a clock signal of the I2C communication standard, andthe voltage fluctuation of the signal line is driven by the open drainconnection. On the other hand, SCLK transmitted by the SCLK contact TC07is a clock signal pursuant to the SPI communication standard, and thevoltage fluctuation of the signal line is driven by the CMOS output.Therefore, the SCL contact TC13 tends to have a gentler edge of thevoltage fluctuation than the SCLK contact TC07, and the clock noises areless likely to occur. Thus, disposing the attachment detection contactTC06 next to the SCLK contact TC07 rather than next to the SCL contactTC13 is more effective in preventing the malfunction caused by the clocknoises.

The differential signals DIN and D1P may be transmitted in pairs to thefirst and second differential signal contacts TC19 and TC20 to transmitthe clock signal. At that time, a clock signal (third clock signal)having a frequency higher than that of the SCLK contact TC07 or the SCLcontact TC13 may be transmitted. Since the differential signals DIN andD1P are paired signals, the emission of the clock noise is smaller thanthat of the SCLK contact TC07 or the SCL contact TC13 that transmits asingle-ended signal. Therefore, disposing the attachment detectioncontact TC06 next to the SCLK contact TC07 rather than next to the firstand second differential signal contacts TC19 and TC20 can moreeffectively prevent the malfunction caused by the clock noise.

The contact (first data contact) TC08 disposed on an opposite side ofthe attachment detection contact TC06 with respect to the SCLK contactTC07 transmits MOSI (first data signal). Since MOSI is a data signal, itappears to be susceptible to clock noises. Since MOSI is a data signalof the same SPI communication standard as the clock signal transmittedby the SCLK contact TC07, the fluctuation timing of the potential issynchronized with the clock signal and is less affected by the clocknoise. Therefore, the contact TC08 does not have to be fixed to the GNDpotential and can be used as a MOSI contact.

The accessory 200 has a battery 205 and receives the power supply fromthe battery 205 and also receives the power supply from the camera 100via the camera connector 141 and the accessory connector 211. Anaccessory control circuit 201 as a control means of the accessory 200 isa circuit that controls the entire accessory 200, and is a microcomputerhaving a built-in CPU and the like.

An accessory power supply circuit 202 is a circuit that generates apower supply to be supplied to each circuit of the accessory 200, andincludes a DC/DC converter circuit, an LDO, a charge pump circuit, andthe like. The voltage 1.8 V generated by the accessory power supplycircuit 202 is constantly supplied as an accessory microcomputer powersupply VMCU_A to the accessory control circuit 201. Turning on and offof the power supply to each circuit of the accessory 200 is controlledby controlling the accessory power supply circuit 202.

A charging circuit 204 is a circuit for charging the battery 205 usingthe power supplied from the camera 100. When it can be determined thatthe sufficient power is supplied from the camera 100 to perform thecharging operation, the accessory control circuit 201 controls thecharging circuit 204 to charge the battery 205. Although the battery 205attached to the accessory 200 has been described in this embodiment, theaccessory 200 may operate only with the power supply from the camera 100without the battery 205. In this case, no charging circuit 204 isnecessary.

A differential communication circuit 207 is a circuit for performing adifferential communication with the camera 100, and can transmit andreceive data to and from the camera 100. An external communication IFcircuit 208 is an IF circuit for performing a data communication with anunillustrated external device, such as an Ethernet communication IF, awireless LAN communication IF, and a public network communication IF.

The accessory control circuit 201 controls the differentialcommunication circuit 207 and the external communication IF circuit 208and thereby can transmit the data received from the camera 100 to theexternal device or the data received from the external device to thecamera 100. A functional circuit 206 is a circuit having a differentfunction depending on the type of the accessory 200. A configurationexample of the functional circuit 206 will be described later.

An external connection terminal 209 is a connector terminal connectableto an external device, and is a USB TYPE-C connector in this embodiment.A connection detecting circuit 210 is a circuit for detecting that anexternal device is connected to the external connection terminal 209,and the accessory control circuit 201 can detect that the externaldevice has been connected to the external connection terminal 209 byreceiving the output signal of the connection detecting circuit 210.

A power switch 203 is a switch for turning on and off the operation ofthe accessory 200, and the accessory control circuit 201 can detect theON position and the OFF position by reading the signal level of theterminal to which the power switch 203 is connected.

The accessory connector 211 is a connector electrically connectable tothe camera 100 via the 21 contacts TA01 to TA21 that are arranged in arow. The contacts TA01 to TA21 are arranged in this order from one endto the other end in the arrangement direction.

TA01 is connected to GND and serves not only as a contact of thereference potential but also as a contact for controlling the wiringimpedance of the differential signals D1N and D1P. TA01 corresponds to athird grounded contact.

The differential signal D1N connected to TA02 and the differentialsignal D1P connected to TA03 are paired data communication signals forthe data communication, and are connected to the differentialcommunication circuit 207. TA02, TA03, TA07 to TA17, TA19, and TA20described later are communication contacts.

TA04 as the first grounded contact is connected to GND and serves as areference potential contact between the camera 100 and the accessory200. TA04 is located outside TA05 described below in the contactarrangement direction.

The accessory power supply circuit 202 and the charging circuit 204 areconnected to TA05 as the power supply contact, and the accessory powersupply VACC supplied from the camera 100 is connected to it.

TA06 as an attachment detection contact is directly connected to GND,and turns the accessory attachment detection signal/ACC_DET describedabove into the GND level as the Lo level when the accessory 200 isattached to the camera 100. Thereby, it becomes it serves as a contactfor causing the camera 100 to detect the attachment of the accessory200.

SCLK connected to TA07, MOSI connected to TA08, MISO connected to TA09,and CS connected to TA10 are signals for the accessory control circuit201 to act as a communication slave and perform the SPI communication.

The communication request signal/WAKE for requesting the communicationfrom the accessory control circuit 201 to the camera 100 is connected toTA11. When the accessory control circuit 201 outputs the communicationrequest signal/WAKE at the Lo level and requests the camera 100 for thecommunication when determining that the communication with the camera100 is necessary.

When the power is supplied from the camera control circuit 101 to theaccessory 200 via TC5 in response to detecting that the accessory 200 isin the attached state, the accessory control circuit 201 notifies thecamera control circuit 101 of the reception of the power supply bychanging the signal level (potential) of the communication requestsignal/WAKE from the Hi level to the Lo level.

The accessory control circuit 201 notifies that the accessory 200 has acause of the communication with the camera 100 by changing the signallevel (potential) of the communication request signal/WAKE from the Hilevel to the Lo level even without any requests from the camera. Withthis configuration, the camera control circuit 101 can omit theoperation of periodically checking whether or not the accessory 200 hasa cause of the communication through polling. In addition, when theaccessary 200 has the cause of the communication, the accessory 200 cancommunicate the fact to the camera 100 on a real-time basis.

SDA connected to TA12 and SCL connected to TA13 are signals for theaccessory control circuit 201 to act as a communication slave andperform the I2C communication.

The FNC1 signal connected to TA14 (synchronous contact), the FNC2 signalconnected to TA15, the FNC3 signal connected to TA16, and the FNC4signal connected to TA17 are signals whose functions can be changedaccording to the type of the accessory 200. For example, when theaccessory 200 is a microphone device, it is an audio data signal, andwhen the accessory 200 is a strobe device, it is a signal forcontrolling the light emission timing. TA14 to TA17 correspond tofunctional signal contacts.

TA18 as the second grounded contact (reference potential contact) isalso connected to GND, and serves as a reference potential contactbetween the camera 100 and the accessory 200, similar to TA04.

The differential signal D2N connected to TA19 (first differential signalcontact) and the differential signal D2P connected to TA20 (seconddifferential signal contact) are paired data communication signals forthe data communication and connected to the external connection terminal209.

TA21 is connected to GND and serves not only as a contact for areference potential but also as a terminal for controlling the wiringimpedance of the differential signals D2N and D2P. TA21 corresponds to afourth grounded contact.

The contacts TA01, TA04, TA06, TA18, and TA21 are connected, forexample, to the GND portion of the flexible substrate 259 illustrated inFIG. 19, which will be described later, and the GND portion of theflexible substrate 259 is fixed to a metallic member having a GND levelof the accessory 200 with an unillustrated screw etc. The metallicmember having the GND level includes, for example, a shoe attachment leg251 and an unillustrated base plate inside the accessory 200.

FIG. 2A illustrates that the accessory connector 211 disposed on theshoe provided on the lower part of the accessory (strobe device) 200 isconnected to the camera connector 141 disposed on the accessory shoeprovided at the top of the camera 100. FIG. 2B illustrates anarrangement example of the 21 contacts TC01 to TC21 in the cameraconnector 141. TC01 is disposed at the right end viewed from the objectside, and the 21 contacts up to TC21 are arranged in a row. Theaccessory shoe is attached by sliding it from the top side to the bottomside in FIG. 2B relative to the accessory shoe having the cameraconnector 141.

FIG. 2C illustrates an arrangement example of the 21 contacts TA01 toTA21 in the accessory connector 211. Similar to the camera connector141, TA01 is disposed at the right end viewed from the object side, andthe 21 contacts up to TA21 are arranged in a row. Usually, the contactsTA01 to TA21 and the corresponding contacts TC01 to TC21 are connectedto each other. However, if an excessive static pressure or impact isapplied to the accessory 200, the contacts may be disconnected. Inparticular, when a force in the rotational direction acts on thedirection in which the contacts are arranged in the accessory 200, thedisconnection is likely to occur at the end contacts.

FIG. 3A exaggerates the appearance of the excessive static pressureapplied to the accessory 200 from the left side viewed from the objectside. At this time, a force acts on the contacts TC21 and TA21 and theneighboring contacts of the camera connector 141 and the accessoryconnector 211 in the disconnecting direction, and a poor connection islikely to occur. On the other hand, a stronger force acts on thecontacts TC01 and TA01 and the neighboring contacts in the connectingdirection than that in the normal state.

FIG. 3B exaggerates the appearance of the excessive static pressureapplied to the accessory 200 from the right side viewed from the objectside. At this time, a force acts on the contacts TC01 and TA01 and theneighboring contacts of the camera connector 141 and the accessoryconnector 211 in the disconnecting direction, and a poor connection islikely to occur. On the other hand, a stronger force acts on thecontacts TC21 and TA21 and the neighboring contacts in the connectingdirections than that in the normal state.

This embodiment connects to GND the contacts TC01 and TA01 and TC21 andTA21 at both ends of the camera connector 141 and the accessoryconnector 211. Thereby, even if a poor connection temporarily occurs atthe contact at one end due to the excessive static pressure, the GNDconnection can be secured at the contact at the other end. Therefore,this configuration can restrain each circuit and electric element fromgetting damaged as a result of that the reference potential of theaccessory 200 becomes unstable due to the poor GND connection.

When the accessory 200 in which part of the GND contacts is missing isattached due to a defect and breakdown of the accessory connector 211 orthe like, the camera control circuit 101 cannot detect that the part ofthe GND contacts is missing. In such a case, the operating currentconcentrates on the remaining GND contacts, and the accessory 200 maymalfunction in some cases.

FIG. 4A is a configuration example for allowing the camera 100 to detectthe connection state of the GND contact of the accessory 200, andillustrates extracted part relating to the grounded contact from theconfiguration illustrated in FIGS. 1.

TC01, TC04, TC18, and TC21 are connected to input terminals P1, P2, P3,and P4 of the camera control circuit 101, respectively, and pulled tothe camera microcomputer power supply VMCU_C via resistors 1011Rp_g1,1021Rp_g2, 1031Rp_g3, and 1041Rp_g4, respectively. An SW circuit 1(1012), an SW circuit 2 (1022), an SW circuit 3 (1032), and an SWcircuit 4 (1042) are connected to TC01, TC04, TC18, and TC21,respectively.

The SW circuit 1 is a switching circuit driven by the control signal ofthe camera control circuit 101, and when it is turned on by the controlsignal, TC01 is connected to GND. It is desirable that the SW circuit 1includes, for example, an FET, or a circuit that has impedance that isas small as possible when the operation is turned on, and the impedancethat is as large as possible when the operation is turned off. Each ofthe SW circuits 2, 3, and 4 also has the same configuration as that ofthe SW circuit 1 as illustrated in FIG. 4A.

A flowchart of FIG. 4B shows a sequence for determining the connectionstate of the grounded terminal in the configuration illustrated in FIG.4A. The camera control circuit 101 executes this processing and otherprocessing described later according to a computer program. S means thestep.

In S1001, the camera control circuit 101 monitors the signal level ofthe accessory attachment detection signal/ACC_DET and determines whetheror not the accessory 200 is attached. If the signal level is Hi, thecamera control circuit 101 returns to S1001 and performs the detectionagain, assuming that the accessory 200 is not attached, and if thesignal level is Lo, it proceeds to S1002 assuming that the accessory 200is attached.

In S1002, the camera control circuit 101 makes such a control that theSW circuit 1 is turned on and the SW circuits 2, 3, and 4 are turnedoff, respectively.

In S1003, the camera control circuit 101 confirms the voltage level ofthe input terminal P1, and determines that TC01 is connected to thegrounded contact if it is a Lo level, and that TC01 is not connected tothe grounded contact if it is a Hi level.

Next, in S1004, the camera control circuit 101 makes such a control thatthe SW circuit 2 is turned on and the SW circuits 1, 3, and 4 are turnedoff, respectively.

In S1005, the camera control circuit 101 confirms the voltage level ofthe input terminal P2, and determines that TC04 is connected to thegrounded contact if it is a Lo level, and that TC04 is not connected tothe grounded contact if it is a Hi level.

Next, in S1006, the camera control circuit 101 makes such a control thatthe SW circuit 3 is turned on and the SW circuits 1, 2, and 4 are turnedoff, respectively.

In S1007, the camera control circuit 101 confirms the voltage level ofthe input terminal P3, and determines that TC18 is connected to thegrounded contact if it is a Lo level, and that TC18 is not connected tothe grounded contact if it is a Hi level.

Next, in S1008, the camera control circuit 101 makes such a control thatthe SW circuit 4 is turned on and the SW circuits 1, 2, and 3 are turnedoff, respectively.

In S1009, the camera control circuit 101 confirms the voltage level ofthe input terminal P4, and determines that TC21 is connected to thegrounded contact if it is a Lo level, and that it is not connected tothe grounded contact if it is a Hi level.

In S1010, the camera control circuit 101 makes such a control that theSW circuits 1, 2, 3, and 4 are turned on, respectively.

Such a control enables the camera control circuit 101 to confirm theattachment state of the grounded contact with the attached accessory200, and to determine whether or not to supply to the accessory powersupply circuit 202 and the like based on the ground connection state.

In the meanwhile, if the accessory 200 is tilted to the camera 100 orthe like when the accessory 200 is attached to the camera 100, only someof the plurality of contacts TC01 to TC21 and TA01 to TA21 can beconnected with each other. As illustrated in FIG. 16, where a Zdirection is the attachment direction of the accessory 200 to the camera100, an X direction is a direction in which the plurality of contactsTC01 to TC21 and TA01 to TA21 are aligned, and a Y direction is adirection orthogonal to the X direction and the Z direction, only someof the contacts may be connected in the following cases.

First, as illustrated in FIGS. 3A and 3B, when the accessory 200 istilted to the camera 100 around an axis parallel to the Z direction,some of the plurality of contacts may be connected with each other onone side where the camera 100 and the accessory 200 are close to eachother but some of the plurality of contacts are disconnected from eachother on the other side where the camera 100 and the accessory 200 areseparated from each other. Although not illustrated, when the accessory200 is tilted (twisted) to the camera 100 around an axis parallel to theY direction, some contacts on an opposite side of the plurality ofcontacts that are connected with each other are separated from eachother.

As detailed later with reference to FIG. 5, in the camera 100 and theaccessory 200 according to this embodiment, the attachment detectionprocessing is executed prior to various communications while theaccessory 200 is attached to the camera 100. At this time, if theattachment detection contacts TC06 and TA06 are connected, theattachment detection processing can be executed. After the attachmentdetection processing via the contacts TC06 and TA06 is executed, thecommunication request signal/WAKE is output from the accessory 200 tothe camera 100 via the contacts (also referred to as communicationrequest contacts hereinafter) TC11 and TA11. By detecting thiscommunication request signal/WAKE, the camera 100 performs variouscommunications, determining that the accessory 200 is in a communicablestate. However, if the camera 100 cannot detect the communicationrequest signal/WAKE even though the attachment of the accessory 200 tothe camera 100 is detected, the camera 100 determines that there is acommunication error with the accessory 200. If the accessory 200 istilted or twisted while the accessory 200 is being attached to thecamera 100, only some of the contacts are temporarily connected, it isdetermined that there is a communication error, and error processing,such as an alarm, is performed, the user may misunderstand that theaccessory 200 breaks down.

Therefore, this embodiment adopts the contact arrangement so as toreduce the occurrence of a situation in which the camera 100 cannotdetect the communication request signal/WAKE even though the attachmentof the accessory 200 to the camera 100 is detected.

As described above, when the accessory 200 is tilted to the camera 100around an axis parallel to the Z direction, the contacts TC01 and TA01and the neighboring contacts are connected as illustrated in FIG. 3A,and the contacts TC21 and TA21 and the neighboring contacts aredisconnected, or the contacts TC21 and TA21 and the neighboring contactsare connected and the contacts TC01 and TA01 and the neighboringcontacts are disconnected as illustrated in FIG. 3B.

This embodiment uses the contacts TC06 and TA06 to detect the attachmentof the accessory 200 to the camera 100. As illustrated in FIG. 3A, whenthe contacts TC01 and TA01 are connected with each other, theneighboring contacts TC06 and TA06 are often connected with each other.At this time, if the communication request contacts TC11 and TA11 arelocated near the distant contacts TC21 and TA21, the camera 100 isunlikely to detect the communication request signal/WAKE even though theattachment of the accessory 200 to the camera 100 is detected.

On the other hand, as illustrated in FIG. 3B, if the contacts TC06 andTA06 are connected with each other while the contacts TC21 and TA21 areconnected with each other, and if the contacts TC11 and TA11 arearranged on a side of the contacts TC01 and TA01 distant from thecontacts TC06 and TA06, the camera 100 is unlikely to detect thecommunication request signal/WAKE even though the attachment of theaccessory 200 to the camera 100 is detected.

On the other hand, this embodiment adopts the following contactarrangement. As illustrated in FIG. 1, the attachment detection contactsTC06 and TA06 and the communication request contacts TC11 and TA11 aredisposed between the contacts TC01 and TA01 closest to one end and thecontacts TC21 and TA21 closest to the other end in the direction inwhich a plurality of contacts TC01 to TC21 and TA01 to TA21 are arranged(referred to as a contact arrangement direction hereinafter). Thisarrangement relationship will be referred to as a first arrangementrelationship. The attachment detection contacts TC06 and TA06 aredisposed between the communication request contacts TC11 and TA11 andthe contacts TC01 and TA01. This arrangement relationship will bereferred to as a second arrangement relationship. Then, in the contactarrangement direction, distances between the attachment detectioncontacts TC06 and TA06 and the communication request contacts TC11 andTA11 are made shorter than distances between the communication requestcontacts TC11 and TA11 and the contacts TC21 and TA21. This arrangementrelationship will be referred to as a third arrangement relationship. Inthis embodiment, the contacts TC01 to TC21 and TA01 to TA21 are arrangedat regular pitches, so that the distance between the contacts herein canbe rephrased as the number of other contacts arranged between thesecontacts, and a short (or long) distance can be rephrased as a small (orlarge) number of other contacts.

In this embodiment, the distances between the communication requestcontacts TC11 and TA11 and the contacts TC01 and TA01 are set to beequal to or less than the distance between the communication requestcontacts TC11 and TA11 and the contacts TC21 and TA21 in the contactarrangement direction. This arrangement relationship will be referred toas a fourth arrangement relationship. In particular, this embodimentdisposes the communication request contacts TC11 and TA11 at the centersbetween the contacts TC01 to TC21 and TC01 to TC21, and makes equal toeach other the distances between the communication request contacts TC11and TA11 and the contacts TC01 and TA01, and the distances between thecommunication request contacts TC11 and TA11 and the contacts TC21 andTA21. The communication request contacts TC11 and TA11 do notnecessarily have to be disposed at the centers between the contacts TC01to TC21 and TC01 to TC21, but they are preferably disposed near thecenters.

This embodiment makes the distances between the attachment detectioncontacts TC06 and TA06 and the contacts TC01 and TA01 equal to orgreater than the distances between the attachment detection contactsTC06 and TA06 and the communication request contacts TC11 and TA11 inthe contact arrangement direction. This arrangement relationship will bereferred to as a fifth arrangement relationship. In particular, thisembodiment disposes the attachment detection contacts TC06 and TA06 atthe centers between the communication request contacts TC11 and TA11 andthe contacts TC01 and TA01, and makes the distances between theattachment detection contacts TC06 and TA06 and the contacts TC01 andTA01 and the distances between the attachment detection contacts TC06and TA06 and the communication request contacts TC11 and TA11 equal toeach other. The attachment detection contacts TC06 and TA06 do notnecessarily have to be disposed at the centers between the communicationrequest contacts TC11 and TA11 and the contacts TC01 and TA01, but it ispreferable to dispose them near the centers.

With the above contact arrangement, the communication request contactsTC11 and TA11 are highly likely to be connected with each other if theattachment detection contacts TC06 and TA06 are connected with eachother in the tilted state illustrated in FIG. 3A, and in the tiltedstate illustrated in FIG. 3B, even if the communication request contactsTC11 and TA11 are connected with each other, the attachment detectioncontacts TC06 and TA06 are highly likely to be disconnected with eachother. As a result, whichever state the accessory 200 is tilted in, theoccurrence of a situation in which the camera 100 cannot detect thecommunication request signal/WAKE can be reduced even though theattachment of the accessory 200 to the camera 100 is detected.

A description will now be given as a comparative example of a case wherethe positions of the contacts TC06 and TA06 and the contacts TC11 andTA11 are exchanged. That is, a description will be given of a case wherethe contacts TC11 and TA11 are used to detect the attachment and thecontacts TC06 and TA06 are used to detect the communication requestsignal/WAKE. In this configuration, when the accessory 200 is tilted tothe camera 100 and the contacts TC01 and TA01 and the neighboringcontacts are disconnected from each other, the contacts TC11 and TA11for the attachment detection may be connected with each other but thecontacts TC06 and TA06 for the communication request signal/WAKE may bedisconnected from each other, resulting in a communication error.

Therefore, in order to avoid the communication error, it is preferableto dispose the attachment detection contact on one end side in thecontact arrangement direction rather than the contacts for thecommunication request signal/WAKE as in this embodiment.

As illustrated in FIGS. 20A to 20C and 23, which will be describedlater, in a configuration where the accessory 200 holds a plurality ofcontacts with a connection plug 256 as a holding member made of anonconductive material such as a resin material, the connection plug 256may have a convex shape toward the lower side (contact direction withthe camera connector 141) in the drawing. In such a case, the contact onone end side in the contact arrangement direction of the plurality ofcontacts is likely to be connected but the contact on the other end sideis likely to be disconnected. However, the contact arrangementillustrated in this embodiment can reduce an occurrence of acommunication error even if some of the contacts are disconnected whenthe accessory 200 is attached to the camera 100.

As described above, when the accessory 200 is twisted relative to thecamera 100 around the axis parallel to the Y direction, some contacts onone end side in the contact arrangement direction of the plurality ofcontacts may be connected, but the other contacts on the other end sidemay be disconnected. When such a state occurs in the process ofattaching the accessory 200 to the camera 100, the connection timingsshift among the plurality of contacts. If the contact timingsignificantly shifts, a time lag from the attachment detection of theaccessory 200 to the camera 100 to the detection of WAKE becomes long,and consequently a communication error may be determined. At this time,depending on the twisting direction of the accessory 200, the side ofthe contacts TC01 and TA01 or the side of the contacts TC21 and TA21starts to be connected first.

When the side of the contacts TC01 and TA01 starts to be connected, thecloser the communication request contacts TC11 and TA11 are to thecontacts TC21 and TA21, the longer the time lag becomes from theattachment detection of the accessory 200 to the detection of thecommunication request signal/WAKE. The longer the time lag is, the moreeasily a communication error is determined. On the other hand, when theside of the contacts TC21 and TA21 starts to be connected and thecommunication request contacts TC11 and TA11 are disposed on the side ofthe contacts TC01 and TA01 of the attachment detection contacts TC06 andTA06, a time lag occurs from the attachment detection of the accessory200 to the detection of the communication request signal/WAKE.

On the other hand, this embodiment adopts the above contact arrangement,and shortens a time lag from the attachment detection of the accessory200 to the detection of the communication request signal/WAKE,regardless of which side of the contacts starts to be connected.

This embodiment disposes at positions between the attachment detectioncontacts TC06 and TA06 and the communication request contacts TC11 andTA11 the contacts TC07 and TA07 to TC10 and TA10 used for the SPIcommunication (communication in the second communication method) betweenthe camera 100 and the accessory 200. The contacts TC12, TA12, TC13, andTA13 used for the I2C communication (communication in the firstcommunication method) between the camera 100 and the accessory 200 aredisposed at positions close to the communication request contacts TC11and TA11 on the opposite side of the attachment detection contacts TC06and TA06.

The communication between the camera 100 and the accessory 200 isexecuted after the camera 100 detects the communication requestsignal/WAKE. Therefore, until the communication between the camera 100and the accessory 200 is executed, the connection of the contacts usedfor the communication is not confirmed. On the other hand, in thisembodiment, if the attachment detection contacts TC06 and TA06 and thecommunication request contacts TC11 and TA11 are connected with eachother, the communication contacts TC07, TA07 to TC10, TA10, TC12, TA12,TC13, and TA13 arranged near and between them, respectively, can beconsidered to be connected.

Since it can be considered that the positions between the attachmentdetection contacts TC06 and TA06 and the communication request contactsTC11 and TA11 are more reliably connected, the contacts used for the SPIcommunication executed after the I2C communication are preferablydisposed at positions between the attachment detection contacts TC06 andTA06 and the communication request contacts TC11 and TA11.

As illustrated in FIG. 4, and FIGS. 12 and 20 which will be used laterfor the explanation, a configuration in which the number of contacts issmaller than that of the camera 100 is conceivable as the configurationof the accessory 200. Even in this configuration, the attachmentdetection contact and the communication request contact are necessarycontacts, and the attachment detection contact and the communicationrequest contact may be arranged under an idea similar to theconfiguration in which the number of contacts is equal to that of thecamera 100. However, a part of the above-mentioned first to fiftharrangement relationships may not be satisfied.

For example, in the configuration having no contact TA21 as illustratedin FIG. 4, a distance between the communication request contact TA11 andthe contact TA01 is longer than a distance between the communicationrequest contact TA11 and the contact TA20 in the contact arrangementdirection. That is, the fourth arrangement relationship is notsatisfied. For example, in a configuration having no contacts TA01 toTA03 and TA19 to 21 as illustrated in FIG. 12, a distance between theattachment detection contact TA06 and the contact TA04 in the contactarrangement direction is shorter than a distance between the attachmentdetection contact TA06 and the communication request contact TA11. Thatis, the fifth arrangement relationship is not satisfied.

As described above, in a configuration in which the position of thecontact position at the end of the accessory 200 is different from thecontact position at the end of the camera 100, part of the first tofifth arrangement relationships may not be satisfied. In such a case, itis assumed that the position facing the contact at the end of the camera100 in the attached state is the position of the contact at the end ofthe accessory 200, and the attachment detection contact and thecommunication request contact may be arranged so as to satisfy the firstto fifth arrangement relationships. Alternatively, as in the protrusion256 a illustrated in FIG. 20, the attachment detection contact and thecommunication request contact may be arranged so as to satisfy the firstto fifth arrangement relationships in consideration of the distance fromthe protrusion 256 a instead of the distance from the contact at theend. A flowchart of FIG. 5A shows processing executed by the cameracontrol circuit 101 when the accessory 200 is attached to the camera100.

In S401, the camera control circuit 101 as an attachment detection meansmonitors the signal level of the accessory attachment detectionsignal/ACC_DET and determines whether or not the accessory 200 isattached. If the signal level is Hi, the camera control circuit 101returns to S401 and performs the detection again, assuming that theaccessory 200 is not attached, and if the signal level is Lo, proceedsto S402 assuming that the accessory 200 is attached.

In S402, the camera control circuit 101 sets a power supply controlsignal CNT_VACC1 to the Hi level in order to turn on the output of theaccessory-use power supply circuit A131, and proceeds to S403. Theaccessory-use power supply circuit A131 outputs the accessory powersupply VACC in response to the power supply control signal CNT_VACC1becoming Hi.

In S403, the camera control circuit 101 monitors the signal level of theovercurrent detection signal DET_OVC and determines whether or not theovercurrent is flowing. If the signal level is Lo, the camera controlcircuit 101 proceeds to S404 assuming that no overcurrent flows, and ifthe signal level is Hi, proceeds to S405 assuming that the overcurrentflows to perform error processing.

FIG. 6A schematically illustrates a change of the signal when the flowproceeds to S404 in the processing of FIG. 5A. IACC is the current ofthe accessory power supply VACC. Since the accessory power supply VACCnormally leads up after the power supply control signal CNT_VACC1 is setto Hi in S402, the overcurrent detection signal DET_OVC remains at a Lolevel.

FIG. 6B schematically illustrates a change in the above signal when theflow proceeds to S405 in the processing of FIG. 5A. Since theovercurrent flows through IACC after the power supply control signalCNT_VACC1 is set to Hi in S402, the overcurrent detection signal DET_OVCchanges to the Hi level and notifies the camera control circuit 101.Upon receiving the notification of the overcurrent detection signalDET_OVC, the camera control circuit 101 turns off the outputs of theaccessory-use power supply circuits A131 and B132 as error processing tostop the power supply to the accessory 200. Thus, even when theovercurrent flows through the accessory power supply VACC, the cameracontrol circuit 101 can detect the overcurrent and safely stop thesystem.

Usually, in a case where an abnormal current flows through the accessorypower supply VACC, it is presumed that the camera 100 and the accessory200 are out of order, but since the camera connector 141 and theaccessory connector 211 are exposed to the outside, and thus theneighboring contacts may be short-circuited due to an adhesion of aforeign matter such as a metal piece.

In this embodiment, the accessory power supply VACC has a voltage of 3.3V, whereas the camera microcomputer power supply VMCU_C and theaccessory microcomputer power supply VMCU_A have a voltage of 1.8 V.Thus, if a voltage of 3.3 V is applied to an electric element operatingat a voltage of 1.8 V, the electric element may get damaged. Since thepost-short-circuiting behavior depends on the characteristic of theelectric element, the camera control circuit 101 may not always be ableto detect the short-circuiting between the terminals. For example, sincethe I2C communication signal is at the Hi level in the communicationstandby state, even if it is short-circuited with the voltage of 3.3 Vequal to and higher than the voltage of 1.8V, the abnormality cannot bedetected depending on the characteristic of the electric element of theconnection destination.

On the other hand, this embodiment disposes the GND contacts TC04 andTA04 on one of the two sides of the accessory power supply VACC contactsTC05 and TA05, and the contacts TC06 and TA06 of the accessoryattachment detection signal/ACC_DET on the other side. As describedabove, the accessory attachment detection signal/ACC_DET is connected toGND in the accessory 200. Thus, even if short-circuiting occurs betweenthe contacts, the overcurrent can be detected and the system can besafely stopped without applying 3.3 V to the element operating at 1.8 V.

As described above, if the accessory power supply VACC is supplied whenthe GND contact is not connected, the reference potential of theaccessory 200 becomes unstable, and consequently each circuit and theelectric element may get damaged. In operating the device, an externalforce may be applied that makes unstable the connection of the connectorterminals. On the other hand, by arranging the accessory power supplyVACC contact and the GND contact adjacent to each other as in thisembodiment, the connection of only the accessory power supply VACCcontact can be more effectively prevented than a case where theaccessory power supply VACC contact and the GND contact are separateterminals.

This embodiment connects the accessory attachment detectionsignal/ACC_DET to GND in the accessory 200, but may connect it to GNDvia a resistor element Rd231 as in the accessory 200 illustrated in FIG.9. The short-circuiting current can be reduced by the connection to GNDvia the resistor element Rd231.

In this case, it is necessary to select the resistor element Rd231having such a resistance value that a voltage of (Rd/(Rp+Rd))×1.8 Vobtained by dividing the voltage of 1.8 V of the camera microcomputerpower supply VMCU_C by the resistor elements Rp134 and Rd231 satisfiesthe Lo level threshold (Vi1) of the camera control circuit 101. Forexample, when a Low level detection threshold value (Vi1) of the cameracontrol circuit 101 is 0.33 times the power supply voltage, theresistance value of the resistor element Rd231 needs to be half or lessof the resistor element Rp134 (10 kΩ). In the example of FIG. 9, theresistance value of the resistor element Rd231 is set to 5 kΩ.

FIG. 5B illustrates processing executed by the camera control circuit101 when the accessory 200 having the configuration illustrated in FIG.9 is attached to the camera 100. Since S411 to S413 are the same as S401to S403 illustrated in FIG. 5A, a description thereof will be omitted.

In S414 after S413, the camera control circuit 101 monitors the signallevel of the accessory attachment detection signal/ACC_DET, anddetermines whether or not the accessory attachment detectionsignal/ACC_DET contacts TC06 and TA06 are short-circuited with theaccessory power supply VACC contacts TC05 and TA05. If the signal levelis Lo, the camera control circuit 101 proceeds to S415 assuming that itis not short-circuited, and if the signal level is Hi, proceeds to S416assuming that it is short-circuited to performs the error processing.

FIG. 6C schematically illustrates the state of the above signal when theaccessory power supply VACC and the accessory attachment detectionsignal/ACC_DET are short-circuited in the accessory 200 having theconfiguration of FIG. 9 to which the resistor element Rd231 (5 kΩ) isadded. After the power supply control signal CNT_VACC1 is set to Hi inS402, no overcurrent flows in IACC because the current is limited by theresistor element Rd231.

On the other hand, the voltage of the accessory power supply VACC isapplied to the accessory attachment detection signal/ACC_DET. As soon asthe signal level of the accessory attachment detection signal/ACC_DETbecomes Hi due to interrupt processing or the like, the camera controlcircuit 101 sets the power control signal CNT_VACC1 to Lo in the errorprocessing and stops outputting the accessory power supply VACC (powersupply to the accessory 200). Thereby, the system can be safely stoppedwithout continuously applying 3.3 V to the terminal of the elementoperating at 1.8 V.

As illustrated in FIG. 10, the accessory 200 may be controlled so thatthe accessory attachment detection signal/ACC_DET becomes a Lo level(GND potential) by the accessory control circuit 201 via an NPNtransistor 212 as a switching means. If the accessory 200 is attached tothe camera 100 in the configuration illustrated in FIG. 1, the cameracontrol circuit 101 can always detect the accessory 200, but in theconfiguration illustrated in FIG. 10, the accessory control circuit 201can notify the attachment of the accessory 200 to the camera 100 at anarbitrary timing.

As illustrated in FIG. 11, the accessory 200 may be configured so as toconnect the resistor element Rd231 in series with the NPN transistor212. In this case, the resistance value needs to be half or less of theresistor element Rp134 (10 kΩ) as in the configuration of FIG. 1.

As described above, even if the power supply contact and the adjacentcontact are short-circuited, this embodiment can maintain the safety ofthe system including the camera 100 and the accessory 200, and restrainthem from getting damaged.

FIG. 7 illustrates an example of the functions of the FNC1 signal to theFNC4 signal as the functional signals connected to the contacts TC14 toTC17 and the contacts TA14 to TA17 for each type of the accessory 200(here, the microphone device and the strobe device).

In the microphone device, the FNC2 signal to the FNC4 signal are used asa digital audio (I2S: Inter-IC Sound standard) data bus to transferaudio data. FIG. 8A illustrates a configuration example of thefunctional circuit 206 when the accessory 200 is a microphone device.

An audio processing circuit 206A1 in the functional circuit 206 is acodec circuit that converts an audio signal input from a microphone206A2 into a digital audio (I2S) data format, and is controlled by theaccessory control circuit 201. The accessory control circuit 201 can setthe sampling frequency and the resolution by controlling the audioprocessing circuit 206A1. In this embodiment, the sampling frequency is48 kHz and the resolution is 32 bits. The microphone 206A2 is, forexample, a MEMS-IC microphone or an electret condenser microphone.

TA14 is the FNC1 signal that is not used as an I2S data bus and isconnected to GND. In this embodiment, the unused functional signal isconnected to GND, but the present invention is not limited to thisembodiment, and a connection to a reference potential may be made as thestable potential other than the GND potential (0V) such as the powersupply potential and the L level (low potential) or H level (highpotential) of the signal.

The FNC2 signal connected to TA15 (DATA contact) is an audio data signal(DATA), which is a signal output from the accessory 200 to the camera100.

The FNC3 signal connected to TA16 (LRCLK contact) is an audio channelclock signal (LRCLK), which is a signal output from the accessory 200 tothe camera 100.

The FNC4 signal connected to TA17 (BCLK contact) is an audio bit clocksignal (BCLK), which is a signal output from the camera 100 to theaccessory 200.

In this embodiment, since the sampling frequency is 48 kHz and theresolution is 32 bits as described above, the LRCLK frequency is 48 kHzand the BCLK frequency is 3.072 MHz. DATA has a maximum frequency of1.536 MHz, which is half a cycle of CLK.

In the contact arrangement according to this embodiment, the referencepotential contacts TA18 and TC18 connected to the GND potential as thereference potential are disposed next to the contacts TA17 and TC17 towhich the FNC4 signal (BCLK) having the highest frequency is connectedamong the functional signal contacts to which the functional signals areconnected. The signal wiring to the accessory shoe interface isgenerally configured with a flexible substrate. In order to reduce theproduct cost, the flexible substrate may have a single-sidedspecification, and the substrate wiring is made in the same arrangementas the contact arrangement. This embodiment disposes the GND contact asthe reference potential contact next to the functional signal contactconnected to the signal having the highest frequency among thefunctional signals. This configuration can suppress radiation noises(EMI) from the functional signal contact, interference with signalsconnected to other contacts, and crosstalk with signals other than theI2S data bus.

This embodiment connects to the GND potential as the reference potentialthe contacts TA18 and TC18 next to the contacts TA17 and TC17 connectedto the FNC4 signal (BCLK) having the highest frequency, but the presentinvention is not limited to this example and the same effect can beobtained even if the connection is made to a stable reference potentialother than the GND potential.

FIG. 8B is an example illustrating a configuration in which audio datais increased relative to FIG. 8A. The purpose of increasing the audiodata is to increase the number of channels and the resolution.

The FNC4 signal connected to TA17 is an audio bit clock signal (BCLK),which is the same as that illustrated in FIG. 8A.

On the other hand, the FNC3 signal connected to TA14 is an audio channelclock signal (LRCLK), which is a signal output from the accessory 200 tothe camera 100.

The FNC2 signal connected to TA15 is an audio data signal (DATA2), whichis a signal output from the accessory 200 to the camera 100.

The FNC1 signal connected to TA16 operates as an audio data signal(DATA2), which is a signal output from the accessory 200 to the camera100.

In this way, when an audio data signal is added to increase the audiodata amount and two signals are used, arranging signals in such orderthat a higher frequency is disposed closer to the GND terminal canprovide a configuration that is relatively highly effective inpreventing crosstalk.

FIG. 8C illustrates a configuration example of the functional circuit206 when the accessory 200 is a strobe device. A light emitting circuit206B1 in the functional circuit 206 is a strobe light emitting circuitincluding an IGBT, a trigger coil, and the like, and controls a lightemission of the light emitter 206B2. The light emitter 206B2 includes axenon tube or the like and emits illumination light to illuminate theobject. A charging circuit 206B3 includes a transformer, a switchingFET, a capacitor, and the like, and accumulates electric charges forcausing the light emitter 206B2 to emit light.

The FNC1 signal connected to TA14 is a light emission synchronizationsignal (STARTX) for controlling the light emission timing of the lightemitter 206B2, and is a signal output from the camera 100 to theaccessory 200. The FNC2 signal to the FNC4 signal are not used in thestrobe device, and no signal is connected to these contacts.

This embodiment makes unused functional signal contacts disconnected(OPEN), but the present invention is not limited to this embodiment, anda connection to a stable reference potential, such as the power supplypotential and the L or H level of the signal, may be made according tothe contacts TC15 to TC17 as connection destinations of the contactsTA15 to TA17.

In the strobe device, only the FNC1 signal is used among the functionalsignals. Although the light emission synchronization signal (STARTX) isnot a periodically generated signal, the camera 100 allocates GND to theFNC1 signal when the microphone device is connected so as to prevent theconfiguration of the camera control circuit 101 from being complicated.

A description will now be given of further features of the contactarrangement according to this embodiment. SDA (first signal) connectedto the contacts TC12 and TA12 as the first signal contacts and SCL(second signal) connected to the contacts TC13 and TA13 as the secondsignal contacts are both signals for the I2C communication. Thesesignals are transmitted by the open drain communication. Since both SDAand SCL are pulled up to the camera microcomputer power supply VMCU_C,they are the signal having a relatively high impedance during thecommunication standby, and easily subject to crosstalk.

Therefore, this embodiment assigns the communication request signal(fourth signal)/WAKE to the contacts TC11 and TA11 as the fourth signalcontacts next to the SDA contacts TC12 and TA12. As described above, thecommunication request signal/WAKE is a signal for making a communicationrequest from the accessory 200 to the camera 100.

FIG. 15A illustrates the timing at which the accessory 200 makes acommunication request to the camera 100 and performs the I2Ccommunication. As illustrated in FIG. 15A, the signal level of thecommunication request signal/WAKE changes from the Hi level to the Lolevel prior to the I2C communication by SCL and SDA. This is because theI2C communication is performed in response to this change. Accordingly,disposing the contacts TC11 and TA11 of the communication requestsignal/WAKE at and near the SDA contact for the I2C communication cankeep SDA of the communication request signal/WAKE from crosstalk.

As illustrated in FIG. 15A, a control to change the signal level of thecommunication request signal/WAKE from the Lo level to the Hi levelafter the I2C communication can keep SDA of the communication requestsignal/WAKE from crosstalk.

The FNC1 signal is assigned to the contacts TC14 and TA14 as the thirdsignal contacts next to the SCL contacts TC13 and TA13. As describedabove, since GND is assigned to the FNC1 signal in the microphonedevice, SCL can be kept from crosstalk.

In the strobe device, the light emission synchronization signal (STARTX:third signal) as the FNC1 signal is assigned to the contacts TC14 andTA14 next to the SCL contacts TC13 and TA13. FIG. 15B illustrates thetiming at which the accessory 200 makes a communication request to thecamera 100, and performs the I2C communication and the strobe lightemission. As illustrated in FIG. 15B, at the timing (period) when thelight emission synchronization signal is output, no I2C communication isperformed between the camera 100 and the accessory 200 in order toprocess the control of the strobe light emission with the highestpriority. In other words, the light emission synchronization signal is asignal whose signal level changes before (or after) the I2Ccommunication, but does not change during the I2C communication. Thisconfiguration can keep SCL of the light emission synchronization signalfrom crosstalk.

Thus, this embodiment disposes the STARTX contact on one of both sidesof the SDA contact and the SCL contact, and disposes the /WAKE contacton the other side, thereby achieving a good I2C communication.

This embodiment sets to an open drain signal, similar to SDA, thecommunication request signal/WAKE connected to the contacts TC11 andTA11 next to the SDA contacts TC12 and TA12. In comparison with apush-pull type communication request signal/WAKE is a push-pull system,crosstalk to SDA can be suppressed when the signal level of thecommunication request signal/WAKE changes.

SCLK connected to the SCLK contacts TC07 and TA07 is a clock signal forthe SPI communication, and operates at a driving frequency of 1 MHz inthis embodiment. In this embodiment, the attachment detection contactsTC06 and TA06 next to the SCLK contacts TC07 and TA07 are used totransmit the accessory attachment detection signal/ACC_DET. As describedabove, the accessory attachment detection signal/ACC_DET is a signalthat has a potential equivalent to GND when the accessory 200 isattached to the camera 100. Therefore, this contact arrangement canprevent crosstalk between SCLK and a signal other than the SPI bus.

MOSI connected to the other contacts TC08 and TA08 next to the SCLKcontacts TC07 and TA07 is a data signal transmitted from the cameracontrol circuit 101 to the accessory control circuit 201 by the SPIcommunication. Generally, the timing at which the MOSI output level inthe SPI communication changes is synchronized with the timing at whichthe SCLK output level changes. Therefore, crosstalk can be suppressedbetween SCLK and MOSI by disposing the MOSI contacts TC08 and TA08 nextto the SCLK contacts TC07 and TA07.

MISO connected to the other contacts TC09 and TA09 next to the MOSIcontacts TC08 and TA08 is a data signal transmitted from the accessorycontrol circuit 201 to the camera control circuit 101 in the SPIcommunication. Generally, the timing at which the MISO output levelchanges in the SPI communication is synchronized with the timing atwhich the SCLK output level changes, similar to MOSI. Therefore, bydisposing the MISO contacts TC09 and TA09 next to the MOSI contacts TC08and TA08, crosstalk between the MOSI and the MISO can be suppressed.

CS connected to the other contacts TC10 and TA10 next to the MISOcontacts TC09 and TA09 is a communication request signal transmittedfrom the camera control circuit 101 to the accessory control circuit 201in the SPI communication. Generally, CS in the SPI communicationmaintains a constant output level from a communication request to acommunication completion. Therefore, by disposing the CS contacts TC10and TA10 next to the MISO contacts TC09 and TA09, crosstalk to MISO canbe suppressed.

The communication request signal/WAKE connected to the contacts TC11 andTAU adjacent to the CS contacts TC10 and TA10 is a signal for making acommunication request from the accessory control circuit 201 to thecamera control circuit 101. As described above, the communicationrequest signal/WAKE is an open drain signal, and thus is relativelysusceptible to crosstalk. Therefore, this embodiment disposes thecontacts TC10 and TA10 for CS whose signal level changes relativelyinfrequently, next to the contacts TC11 and TA11 for the communicationrequest signal/WAKE, and can suppress crosstalk to the communicationrequest signal/WAKE.

A differential signal that requires an impedance control is connected tothe contacts TC01 to TC03 and TA01 to TA03 and the contacts TC19 to TC21and TA19 to TA21 located at and near both ends of the camera connector141 and the accessory connector 211 (these will be collectively referredto as both end sides hereinafter). The signal wiring to the accessoryshoe interface is generally configured with a flexible substrate. Inorder to achieve the desired wiring impedance on the flexible board, itis necessary to keep a distance between the lines of the differentialsignal and with GND to be wired in parallel. In a board in which bothsides are used, it is common to form a mesh GND wiring on the backsideof the differential signal. Thus, the signal wiring that requires theimpedance control has relatively large restrictions on the wiring designin comparison with a general single-ended signal.

On the other hand, this embodiment connects the differential signal thatrequires an impedance control to the contacts located on both ends ofthe camera connector 141 and the accessory connector 211, therebyrelatively reducing a relationship with other signals and improving thedegree of freedom in wiring design.

The differential signal can be transferred at a high speed of aboutseveral hundred Mbps to several Gbps such as USB and PCIe, and issuitable to transfer a large data amount between devices. On the otherhand, no differential signal may be used depending on the type of theaccessory 200. The accessory that uses no differential signal needs nocontacts assigned to the differential signal, so the accessory cost canbe reduced by deleting the contact.

FIG. 12 illustrates a configuration variation of the accessory 200illustrated in FIG. 1. More specifically, it has such a configurationthat the contacts TA01 to TA03 and TA19 to TA21 and signals and circuitsconnected to them are omitted. That is, the accessory 200 in FIG. 12 has15 contacts. In the configuration in FIG. 12, a differential signal isassigned to the contacts TC01 to TC03 and TC19 to TC21 located at bothends of the camera connector 141. On the other hand, the accessory 200that needs no differential signal adopts a contact arrangement thateliminates a contact for the differential signal from the accessoryconnector 211, and includes only the contact necessary for the accessory200.

The accessory 200 in FIG. 12 sets to the GND contacts the contacts TC04and TA04 and the contacts TC18 and TA18 near both ends of the cameraconnector 141 and the accessory connector 211. With such a contactarrangement, even in the accessory 200 connected to a part of thecontacts of the camera connector 141, the contacts at both ends of theaccessory connector 211 can be set to the GND contacts. Thisconfiguration can prevent the GND contacts from being disconnected evenwhen an excessive static pressure or impact is applied to the accessory200.

A direct attachment of the accessory 200 to the camera 100 has beendescribed. Referring now to FIG. 13, a description will be given of anintermediate accessory 300 attached between the camera 100 and theaccessory 200. The camera 100 and the accessory 200 have theabove-described configurations. The intermediate accessory 300 includesan extension cable for extending a distance between the camera 100 andthe accessory 200, an adapter used to simultaneously attach a pluralityof accessories to the camera 100, and the like. This embodiment willdescribe the intermediate accessory 300 as an extension cable. In theconfiguration in FIG. 13, the intermediate accessory 300 corresponds toan accessory, and the accessory 200 corresponds to another accessory.

The intermediate accessory 300 has a camera shoe and an accessory shoethat are attachable to the camera 100 and the accessory 200,respectively, and each is provided with a camera-side intermediateconnector 311 and an accessory-side intermediate connector 312. Thecamera-side intermediate connector 311 has 21 contacts TM01 to TM21arranged in a row, and is a connector for making an electricalconnection with the camera 100. The contacts TM01 to TM21 each make aone-to-one contact with the contacts TC01 to TC21 in the cameraconnector 141.

On the other hand, the accessory-side intermediate connector 312 has 21contacts TN01 to TN21 arranged in a row, and is a connector for makingan electrical connection with the accessory 200. The contacts TN01 toTN21 each make a one-to-one contact with the contacts TA01 to TA21 inthe accessory connector 211.

The intermediate accessory 300 having this contact arrangement canprovide the power supply and the communication in the same manner asthose when the accessory 200 is directly attached to the camera 100. Atthis time, the intermediate accessory 300 may receive the power supplyfrom the camera 100, or the power supply from the camera 100 may bedirectly transmitted to the accessory 200. The power supply in thisembodiment includes a case where the power supply from the camera 100 istransmitted to the accessory 200 as it is and no power is supplied tothe accessory 300.

In FIG. 13, the number of contacts of the camera-side intermediateconnector 311 is the same as the number of contacts of the cameraconnector 141, and the number of contacts of the accessory-sideintermediate connector 312 is the same as the number of contacts of theaccessory connector 211, but they may not necessarily be equal to eachother.

FIG. 14 illustrates a variation of the configuration of FIG. 13 aboutthe accessory 200 and the intermediate accessory 300. Althoughdifferential signals are connected to the contacts TC01 to TC03 and TC19to TC21 on both ends of the camera connector 141, the differentialsignal may not be required depending on the function of the accessory200. The configuration of FIG. 14 eliminates the contact to which thedifferential signal is connected, from the camera-side intermediateconnector 311 and the accessory-side intermediate connector 312 and theaccessory connector 211. That is, the intermediate accessory 300 and theaccessory 200 in FIG. 14 each have 15 contacts. Thereby, a contactarrangement including only the contacts required for the intermediateaccessory 300 and the accessory 200 is adopted.

A detailed description will now be given of the connection configurationbetween the camera 100 and the external flash unit 120, which is anexample of the accessory 200.

FIG. 16A illustrates the camera 100 viewed from the diagonally rearside. FIG. 16B illustrates how to attach the external flash unit 120 tothe accessory shoe 1123 of the camera 100. FIG. 16C illustrates theexternal flash unit 120 attached to the camera 100 viewed from theoblique rear side.

The imaging optical system is provided on the front side (field side) ofthe camera 100, and the image display unit 107 is provided on the rearside of the camera 100. A top cover 150 as an exterior member isprovided on the top surface of the camera 100, and an accessory shoe1123 is provided to the top cover 150. On the other hand, in theexternal flash unit 120, the camera connector 206 is provided at thebottom of the external flash unit 120.

As illustrated in FIG. 16B, the external flash unit 120 is slid in adirection parallel to the front side in the Z direction (attachment sidein the first direction) relative to the camera 100 to engage the cameraconnector 206 and the accessory shoe 1123 with each other. Thereby, theexternal flash unit 120 can be attached to the camera 100. The frontside in the Z direction is a direction from the rear side to the frontside of the camera 100, that is, a direction from the image display unit107 side toward the imaging optical system 122 side. An X direction(second direction), a Y direction (third direction), and the Z direction(front-back direction) illustrated in FIG. 16 and subsequent figures arecommonly used. The X direction is a direction orthogonal to the Zdirection in the horizontal plane when the Z direction is parallel tothe horizontal direction, and is the width direction of the camera 100.The Y direction is a direction orthogonal to the Z direction and the Xdirection, and is the height direction of the camera 100.

A detailed description will now be given of the accessory shoe 1123 ofthe camera 100. FIG. 17A illustrates the top cover 150 and the explodedaccessory shoe 1123. FIG. 17B illustrates the assembled accessory shoe1123. The assembly direction of the accessory shoe 1123 onto the topcover 150 is the Y direction.

The accessory shoe 1123 includes an engagement member 151, a connectionterminal connector 152, a shoe stage 153, and an accessory shoe spring154. The engagement member 151 is a member for holding the externalflash unit 120 through an engagement with the external flash unit 120.The connection terminal connector 152 includes a plurality of connectionterminals 152 a arranged at regular pitches in the X direction on aconnector base member 152 e as a holding member made of a resin materialor the like and held by the connector base member 152 e. The connectionterminals 152 a correspond to the contacts TC01 to TC21 in the cameraconnector 141 illustrated in FIG. 1.

In the connection terminal connector 152, the connection terminals 152 aare arranged on the front side in the Z direction as the attachmentdirection of the external flash unit 120 (on the front side of thecamera 100) as illustrated in FIG. 17B. An engagement hole portion 156to be engaged with a lock pin 252 of the external flash unit 120illustrated in FIG. 19A is provided behind the connection terminalconnector 152 in the Z direction (on the rear side of the digital camera100).

While the external flash unit 120 is attached to the accessory shoe1123, the connection terminals 152 a are electrically connected to theexternal flash unit 120. Each of the plurality of connection terminals152 a is electrically connected to a flexible substrate 158 disposed onthe lower side of the top cover 150 in the Y direction. The flexiblesubstrate 158 is connected to an unillustrated main substrate of thecamera 100. Thus, when the external flash unit 120 is attached to theaccessory shoe 1123, a communication is available between the externalflash unit 120 and the camera 100.

The shoe stage 153 is a housing member that encloses the engagementmember 151 and the connection terminal connector 152. An accessory shoeholding member 155 is a structural skeleton that holds the engagementmember 151. As illustrated in FIG. 17A, the accessory shoe holdingmember 155, the flexible substrate 158, the top cover 150, the shoestage 153, and the connection terminal connector 152 are fastened to theengagement member 151 by four screws 157 that are inserted into them.Thereby, these members are mutually positioned and fixed. By arrangingthe four screws 157 one by one in four areas equally divided in the Xdirection and the Z direction, the above components can be connected ina well-balanced manner.

FIG. 18A illustrates the structure on the top surface side of theengagement member 151, and FIG. 18B illustrates the structure on thebottom surface side of the engagement member 151. FIG. 18C illustratesthe structure of the connection terminal connector 152 on the topsurface side. FIG. 24 illustrates the accessory shoe 1123 viewed fromthe insertion direction of the external flash unit 120.

The engagement member 151 is formed by bending a metal plate in a loopshape so that the end surfaces of the bent ends face and contact eachother at a seam 151 a. The engagement member 151 has a pair ofengagement portions 151 b, and a coupler 151 c that couples the pair ofengagement portions 151 b together. The engagement member 151 has a pairof first screw hole portions 151 d used for fastening the screws 157 anda pair of second screw hole portions 151 e. The engagement member 151has engagement hole portions 156 to be engaged with the lock pins 252 ofthe external flash unit 120.

As illustrated in FIGS. 18A and 12, the pair of engagement portions 151b are separated by a first width (referred to as engagement portioninterval hereinafter) 151 aa in the X direction. A holding member 254 ofthe external flash unit 120, which will be described later, illustratedin FIG. 19B is inserted into the engagement portion interval 151 aa. Thepair of first screw hole portions 151 d are provided at a predeterminedinterval in the X direction, and serve as a pair of first fastening holeportions provided apart from each other in the X direction at the back(on the rear side) in the Z direction. The pair of second screw holeportions 151 e are provided at a predetermined interval in the Xdirection, and serve as a pair of second fastening hole portionsprovided apart from each other in the X direction at the front in the Zdirection. The engagement hole portion 156 is formed at a positionengageable with the lock pin 252 of the external flash unit 120 in anarea sandwiched between the pair of first screw hole portions 151 d.

In the connection terminal connector 152, as illustrated in FIGS. 17Band 18C, a plurality of connection terminals 152 a are exposed. In thepitch direction (X direction) in which the plurality of connectionterminals 152 a are aligned, the position of the camera connector 206 isdetermined by the engagement portion interval 151 aa of the engagementmember 151. Therefore, the holding member 254 of the external flash unit120 is positioned relative to the connection terminal connector 152 bythe engagement member 151.

A contact surface and a groove portion illustrated in FIG. 24 are formedon both sides of the connection terminal connector 152 (connector basemember 152 e) as one example of the camera connector 141 illustrated inFIG. 1 sandwiching the plurality of connection terminals 152 a in the Xdirection on the front side in the Z direction. That is, there areformed contact surfaces 152 b that contact and position the accessoryshoe 1123 in the Z direction when the external flash unit 120 isattached, and groove portions 152 c into which the accessory shoe 1123is inserted. Each groove portion 152 c is formed so as to extend fromthe contact surface 152 b to the front side (attachment side) in the Zdirection, and has a slope portion 152 d so as to face inwardly anddiagonally upwardly (so as to have a tilt to the X direction). Part ofthe groove portion 152 c above the slope portion 152 d extends outwardlyin the X direction from the position of the top end of the slope portion152 d. This is to prevent a dent (sink) from being generated in theslope portion 152 d during resin molding if the slope portion 152 d isformed up to the top end of the groove portion 152 c.

As illustrated in FIG. 24, in the X direction, an outermost innersurface 152 ccc of the groove portion 152 c in the connector base member152 e of the accessory shoe 1123 is located outside of the inner endsurfaces of the pair of engagement portions 151 b of the engagementmember 151 (engagement portion interval 151 aa) and is located inside ofthe outermost inner surface 151 bb of the engagement member 151.

A slope start position 152 cc, which is the end (lower end) of the slopeportion 152 d on the bottom surface side of the groove portion 152 c, isprovided inside the engagement portion interval 151 aa. Thereby, it ispossible to secure an area for providing the contact surface 152 b thatcomes into contact with a contact portion 251 b described later of thecamera connector 206 and positions it in the Z direction. Providing theslope shape starting from the slope start position 152 cc can expand aspace into which the shoe apparatus (camera connector 206 describedlater) of the external flash unit 120 is inserted, and can secure thedegree of freedom in the shape of the shoe apparatus. As a result, theshoe apparatus of the external flash unit 120 can be sufficiently formedwith a shape that protects the connection terminals.

A description will now be given of the external flash unit 120. FIG. 19Aillustrates the external flash unit 120 viewed from the camera connector206 side (bottom side in the Y direction). FIG. 19B is a section takenalong a line A-A in FIG. 19A and illustrates the internal structure ofthe camera connector 206. FIG. 20A illustrates the camera connector 206.However, a base portion 250 and a lock lever 253, which will bedescribed later, are omitted. FIG. 20B illustrates the camera connector206 viewed from the front in the Z direction.

The camera connector 206 is provided on the bottom side in the Ydirection (top side in FIG. 19A) of the base portion 250 of the externalflash unit 120 as illustrated in FIG. 19B when it is attached to theaccessory shoe 1123 of the camera 100. The camera connector 206 includesa shoe attachment leg (engagement member, shoe plate) 251, the lock pins252, a lock lever 253, a holding member 254, a connection plug 256, anda Y-direction holding member 258.

The shoe attachment leg 251 is an engagement member that engages theexternal flash unit 120 with the accessory shoe 1123 of the camera 100and holds it. That is, the shoe attachment leg 251 is an engagementmember on the external flash unit 120 side attachable to and detachablefrom the engagement member 151 of the accessory shoe 1123.

A large stress is applied to the accessory shoe 1123 and the cameraconnector 206 due to the pressure for maintaining the attachment stateand the external force (impact, etc.) acting on the external flash unit120. The shoe attachment leg 251 is manufactured by processing a metalplate (sheet metal) in order to secure a high mechanical strengthagainst such a large stress.

The lock pin 252 is a member for preventing the external flash unit 120from falling off while the camera connector 206 (shoe attachment leg251) is attached to the accessory shoe 1123, and is held on the shoeattachment leg 251 movable in the Y direction. More specifically, thelock pin 252 is slidably held in the Y direction by the Y-directionholding member 258. The lock lever 253 and the Y-direction holdingmember 258 are held by the holding member 254.

When the external flash unit 120 is attached to the accessory shoe 1123and the lock lever 253 is rotated, the Y-direction holding member 258 ismoved downwardly in the Y-direction in FIG. 19B by an unillustrated camportion. At that time, the lock pin 252 also moves downwardly in the Ydirection in FIG. 19B together with the Y-direction holding member 258.Thereby, the lock pin 252 projects from the shoe attachment leg 251 andis engaged with the engaging hole portion 156 provided in the engagementmember 151 of the accessory shoe 1123. The lock pin 252 and theengagement hole 156 serve as a positioning member in the Z direction forensuring an electrical connection between the external flash unit 120and the camera 100.

The connection plug 256 as one example of an accessory connector 211illustrated in FIG. 1 is provided on the front side in the Z directionof the camera connector 206, made of a nonconductive material(dielectric material) such as a resin material, and integrated with theholding member 254. An outermost width T of the connection plug 256 inthe X direction is narrower than a width W of the shoe attachment leg251 in the X direction. Thereby, an area for providing the contactportion 251 b on the shoe attachment leg 251 is secured. The connectionplug 256 has a plurality of connection terminals 257 for contacting andcommunicating with the plurality of connection terminals 152 a of theaccessory shoe 1123 illustrated in FIG. 18C. The connection terminals257 correspond to the contacts TA01 to TA21 of the accessory connector211 illustrated in FIG. 1.

The plurality of connection terminals 257 are provided so as to have aone-to-one correspondence with the plurality of connection terminals 152a, and held by the holding member 254 so as to extend in the Z directionand to line up in the X direction. Each connection terminal 257 has atip portion 257 a that comes into contact with the correspondingconnection terminal 152 a. Each connection terminal 257 has a shapeextending backwardly in the Z direction from a tip portion 257 a, andhas an extension portion 257 b that displaces the tip portion 257 aupwardly in the Y direction in FIG. 19B by an elastic deformation whenthe tip portion 257 a comes into contact with the connection terminal152 a. A vertical extension portion 257 c extending upwardly in the Ydirection is formed at the back end of the extension portion 257 b inthe Z direction. Provided at the upper end of the vertical extensionportion 257 c is a flexible substrate connector 257 d to be connected toan unillustrated main substrate of the external flash unit 120 andconnected to a flexible substrate 259 inserted into the holding member254 from the top side in the Y direction.

The extension portion 257 b has a step portion 257 e having a step inthe Y direction in the middle of the Z direction. As described above,the extension portion 257 b can be elastically deformed in the Ydirection. However, when the distance L in the Z direction of theextension portion 257 b is short, a sufficient deformation amount cannotbe obtained, and the durability is lowered. As a result, the connectionterminal 152 a and the tip portion 257 a are repeatedly attached anddetached, and the extension portion 257 b may easily get damaged.Accordingly, providing the step portion 257 e to the extension portion257 b can secure a sufficient distance L without causing the extensionportion 257 b to interfere with the shoe attachment leg 251.

As illustrated in FIGS. 20A and 20B, there are a pair of protrusionportions 256 a that project downwardly in the Y direction (thirddirection) so as to sandwich a plurality of connection terminals 257 atboth ends of the connection plug 256 in the X direction. As illustratedin FIG. 20B, a lower tip portion 256 d of each protrusion portion 256 aprotrudes below a line made by connecting the lower ends of the tipportions 257 a of the connection terminals 257 in order to protect theconnection terminals 257 from external forces such as the pressure andthe impact. That is, the tip portions 257 a of the connection terminals257 is provided above (inside) a line made by connecting the lower tipportions 256 d of the pair of protrusion portions 256 a.

There is a slope portion 256 b on the outer side (outer surface) of eachprotrusion portion 256 a in the X direction, which serves as an outersurface that extends diagonally upwardly from the lower tip portion 256d and faces diagonally downwardly, that is, has a tilt to the Xdirection. Since each protrusion portion 256 a has such a shape, theconnection plug 256 can be inserted into the groove portion 152 c havingthe slope portion 152 d in the connection terminal connector 152.

The slope portion 256 b has a role of releasing an external force, suchas the pressure and impact, from the connection plug 256 to prevent theconnection plug from getting damaged. For example, FIG. 20C illustratesthat an external force is applied to the connection plug 256 from the Xdirection. FIG. 20C illustrates the connection plug 256 viewed from thefront in the Z direction.

An external force from the X direction is defined as F₁ as a vector. Theexternal force F₁ acting on the slope portion 256 b is decomposedaccording to the addition theorem in the vector space into a componentforce F₂ in a direction along the slope portion 256 b and a componentforce F₃ in a direction perpendicular to the slope portion 256 b. Whereθ is an angle formed by the external force F₁ and the slope portion 256b, the component force F₂ and the component force F₃ can be calculatedby the following expression (1).

F₂=F₁ cosθ

F₃=F₁ sinθ  (1)

When the slope portion 256 b is provided, θ is 0°<θ<90°. In this range,the following is established:

F₂<F₁

F₃<F₁   (2)

Since the component force F₂ escapes in the direction along the slopeportion 256 b, the component force F₃ is the only force that affects theconnection plug 256. As described above, since the component force F₃ issmaller than the component force F₁, the connection plug 256 can beprevented from getting damaged even if an external force that is largeto some extent is applied.

By forming the slope portions 256 b on both sides in the X direction sothat its width in the X direction becomes narrower toward the lower sidein the Y direction, not only the external force from the X direction butalso the external force from the bottom side in the Y direction can bepartially released.

FIG. 25 illustrates the partially enlarged connection plug 256 viewedfrom the Z direction. In the Y direction, assume that B is a height fromthe lower tip portion 256 d of the protrusion portion 256 a to the topsurface of the connection plug 256 (a height of the connection plugincluding the protrusion portion), and A is a height of the slopeportion 256 b from the lower tip portion 256 d (slope start position 256c) to the upper end of the slope portion 256 b. At this time, A ispreferably one-fifth or more of B, more preferably one-fourth or more,one-third or more, or half or more as illustrated in FIG. 13. That is,the slope portion 256 b is formed to have a significant size for thefunction of releasing the external force from the X direction, and isdifferent from a chamfered shape generally provided at the corner of theprotrusion portion. The tilt angle θ of the slope portion 256 b to the Xdirection is preferably set in a range of 45°±20° for the above functionof releasing the external force.

In order to secure a sufficient area for the contact portion 251 b onthe shoe attachment leg 251 relative to the contact surface 152 b of theaccessory shoe 1123 as the positioning portion in the Z direction, it ispreferable to make as short as possible the width in the X directionbetween slope start positions 256 c at the lower tip portions 256 d ofthe slope portions 256 b on both sides. This embodiment sets the widthbetween the slope start positions 256 c in the X direction inside thewidth V of the holding member 254 in the X direction, and therebysecures a sufficient area of the contact portion 251 b.

The camera connector 206 has such a structure that the shoe attachmentleg 251 and the holding member 254 are fastened. The details of thisfastening structure will be described later.

The holding member 254 can be inserted into the engagement portioninterval 151 aa of the engagement member 151 of the accessory shoe 1123illustrated in FIG. 18A, and has a coupler 254 a having a width Vshorter than the width W of the shoe attachment leg 251 in the Xdirection. The widths W and V are defined by the Japanese IndustrialStandards (JIS) B7101-1975 “camera accessory attachment seat andattachment foot.” When the coupler 254 a is engaged with the engagementmember 151, the position of the external flash unit 120 relative to thecamera 100 is determined in the X direction. The shoe attachment leg 251is urged upwardly in the Y direction when it comes into contact with theelastic deformer 154 a of the accessory shoe spring 154 as the urgingmember illustrated in FIGS. 17A and 17B. Thereby, the top surface of theshoe engagement portion 251 a is brought into contact (pressure contact)with the bottom surface of the engagement member 151, and the positionof the external flash unit 120 relative to the camera 100 is determinedin the Y direction.

When the contact portion 251 b of the shoe attachment leg 251 contactsthe contact surface 152 b on the front side in the Z direction of theconnection terminal connector 152, the position of the external flashunit 120 relative to the camera 100 is determined in the Z direction.

The holding member 254 is also a structure for coupling the shoeattachment leg 251 and the base portion 250, and the lock pins 252 andthe connection terminals 257 are arranged inside the coupler 254 a.

Next follows a description of the fastening structure between theholding member 254 and the shoe attachment leg 251. FIG. 21A illustratesthe camera connector 206 viewed from the upper side in the Y direction,and FIG. 21B illustrates a section taken along a line B-B in FIG. 21A.

A pair of first screw 260 a and a pair of second screws 260 b, which arefastening members for fastening the shoe attachment leg 251 to theholding member 254, penetrate the holding member 254 and are fastened tothe shoe attachment leg 251. At this time, by disposing one screw ineach of the four areas that are substantially equally divided in the Xdirection and the Z direction in a well-balanced manner, the shoeattachment leg 251 is stably held by the holding member 254. Asdescribed above, the shoe attachment leg 251 is a component to which alarge stress is applicable. Therefore, a required mechanical strengthcan be ensured by fastening the metal shoe attachment legs 251 to theholding member 254 with a pair of first screws 260 a and a pair ofsecond screws 260 b arranged in a well-balanced manner.

As illustrated in FIG. 21B, a plurality of connection terminals 257 arearranged in an area S sandwiched by the pair of first screws 260 a andthe pair of second screws 260 b. The widths between the pair of firstscrews 260 a and between the pair of second screws 260 b are narrowerthan the width between the lower tip portions 256 d of the protrusionportions 256 a of the connection plug 256, the width V of the holdingmember 254, the outermost width T of the connection plug 256, and thewidth W of the shoe attachment leg 251.

FIG. 26 illustrates a section of the accessory shoe 1123 viewed from theZ direction while the camera connector 206 is attached to the accessoryshoe 1123. This figure illustrates the sizes T and V of the cameraconnector 206 and the positional relationship between each component ofthe camera connector 206 and each component of the accessory shoe 1123.

In FIG. 26, as described above, the top surface of the shoe engagementportion 251 a of the camera connector 206 contacts the bottom (ceilingsurface) of the engagement member 151 of the accessory shoe 1123 forpositioning in the Y direction.

On the other hand, none of the lower tip portion 256 d and the slopeportion 256 b of the protrusion portion 256 a of the connection plug 256in the camera connector 206 contact the bottom surface and the slopeportion 152 d of the groove portion 152 c of the accessory shoe 1123,respectively. A gap between the lower tip portion 256 d of theprotrusion portion 256 a and the bottom surface of the groove portion152 c of the accessory shoe 1123 is set as small as possible. Thereby,when an external force in the X direction is applied to the externalflash unit 120, the lower tip portion 256 d of the protrusion portion256 a can come into contact with the bottom surface of the grooveportion 152 c of the accessory shoe 1123, and a floating amount of theconnection plug 256 (a tilt to the accessory shoe 1123) can be reduced.

Each of a gap between the slope portions 256 b and 152 d and a gapbetween the inner end surface 152 ccc of the groove portion 152 c andthe outer end surface of the connection plug 256 is set to be large tosome extent. Thereby, when an external force in the X direction isapplied to the external flash unit 120, the connection terminals 257 and152 a can be prevented from getting loaded.

In the groove portion 152 c of the accessory shoe 1123, a relationshipbetween a height of the groove portion 152 c in the Y direction (aheight from the bottom surface of the groove portion 152 c to a ceilingsurface of the engagement member 151) and a height of the slope portion152 d in the Y direction is similar to a relationship between the heightB of the connection plug 256 and the height A of the slope portion 256 bin the camera connector 206. It is also preferable that the tilt angleof the slope portion 256 b to the X direction is also set in the rangeof 45°±20°, similarly to the tilt angle θ of the slope portion 256 b inthe camera connector 206.

Each embodiment described above has described a surface shape of theslope portion 256 b provided on the protrusion portion 256 a being flat,but the slope portion 256 b may be a curved surface having a curvature.That is, the slope portion 256 b may have a surface with a tilt to the Xdirection.

This embodiment can secure an area for providing a larger number ofconnection terminals than ever and a shape for protecting them and anarea for positioning between components, in the compact camera connector206 and accessory shoe 1123.

A description will now be given of a variation of an external flash unit120. FIG. 22A illustrates the external flash unit 120 viewed from thecamera connector 206 side (lower side in the Y direction). FIG. 22Billustrates a section taken along a line A-A in FIG. 22A and illustratesthe internal structure of the camera connector 206. FIG. 23A illustratesthe camera connector 206. However, the base portion 250 and the locklever 253 are omitted. FIG. 23B illustrates the camera connector 206viewed from the front in the Z direction.

The camera connector 206 is provided on the lower side in the Ydirection (upper side in FIG. 22A) of the base portion 250 of theexternal flash unit 120 as illustrated in FIG. 22B while it is attachedto the accessory shoe 1123 of the camera 100. The camera connector 206has a shoe attachment leg 300 a, lock pins 252, a lock lever 253, aholding member 300, a connection plug 300 b, a Y-direction holdingmember 258, and a shoe cover 301.

The shoe attachment leg 300 a is an engagement member for engaging theexternal flash unit 120 with the accessory shoe 1123 of the camera 100,similar to the shoe attachment leg 251 of the above-describedembodiment. That is, the shoe attachment leg 300 a is an engagementmember on the external flash unit 120 side attachable to and detachablefrom the engagement member 151 of the accessory shoe 1123.

In the above-described embodiment, the shoe attachment leg 251 as ametal shoe plate and the resin holding member 254 are formed as separatemembers in order to give priority to the mechanical strength. On theother hand, in this variation, the shoe attachment leg 300 a and theholding member 300 are formed as an integrated member by a resinmaterial (nonconductive material). Thereby, the pair of first screws 260a and the pair of second screws 260 b described in the previousembodiment are not required, a space for arranging the connectionterminals 257 becomes wider, and thus a larger number of connectionterminals 257 can be arranged. As a result, the external flash unit 120can communicate more information with the camera 100 via the cameraconnector 206 and the accessory shoe 1123.

The connection plug 300 b is provided on the front side in the Zdirection of the camera connector 206, and formed as an integratedmember with the holding member 300 made of a nonconductive resinmaterial in this embodiment. Similar to the above-described embodiment,the outermost width T of the connection plug 300 b in the X direction ismade narrower than the width W of the shoe attachment leg 300 a in the Xdirection, so that the area for providing the contact portion 300 e issecured in the shoe attachment leg 300 a. The connection plug 300 b hasa plurality of connection terminals 257 for contacting and communicatingwith the plurality of connection terminals 152 a of the accessory shoe1123 illustrated in FIG. 18C. The shoe cover 301 is an enclosureattached to the holding member 300, and is a member that protects aplurality of connection terminals 257. The shape of the connectionterminal 257 is similar to that of the above embodiment, and the stepportion 257 e is provided to secure a sufficient distance L in the Zdirection of the extension portion 257 b without interfering with theshoe cover 301.

The shape of the connection plug 300 b is also similar to that of theconnection plug 256 of the previous embodiment, and a pair of protrusionportions 300 c that project downwardly in the Y direction are providedso as to sandwich the plurality of connection terminals 257 at both endsof the connection plug 300 b in the X direction. As illustrated in FIG.23B, a lower tip portion 300 k of each protrusion portion 300 c projectsbelow a line made by connecting the lower ends of the tip portions 257 aof the connection terminals 257 in order to protect the connectionterminal 257 from the external force such as the pressure and theimpact. That is, the tip portion 257 a of the connection terminal 257 isprovided above (inside) a line made by connecting the lower tip portions300 k of the pair of protrusion portions 300 b.

Even in this embodiment, provided on the outer side of each protrusionportion 300 c in the X direction is a slope portion 300 f that extendsdiagonally upwardly from the lower tip portion 300 k and facesdiagonally downwardly. Each protrusion portion 300 c having such a shapeenables the connection plug 300 b to be inserted into the groove portion152 c having the slope portion 152 d in the connection terminalconnector 152 described in the previous embodiment. As described in theprevious embodiment, the slope portion 300 c has a role of releasing theexternal force such as the pressure and the impact on the connectionplug 300 b to prevent the connection plug from getting damaged.

Similar to the previous embodiment, it is desirable to make as short aspossible a distance in the X direction between the slope start positions300 g at the lower tip portion 300 k of the slope portions 300 c on bothsides. Therefore, the slope start positions 300 g on both sides areprovided inside the width V of the holding member 254 in the X directionto sufficiently secure the area of the contact portion 300 e of the shoeattachment leg 300 a.

The holding member 300 is formed so that it can be inserted into andengaged with the engagement portion interval 151 aa of the engagementmember 151 illustrated in FIG. 18A, and has a coupler 300 h having awidth V shorter than the width W of the shoe attachment leg 300 a in theX direction. The width W and the width V are defined by the JapaneseIndustrial Standards (JIS) B7101-1975 “camera accessory attachment seatand attachment foot” as in the previous embodiment. When the coupler 300h is engaged with the engagement member 151, the position of theexternal flash unit 120 relative to the camera 100 is determined in theX direction. The shoe attachment leg 300 a is urged upwardly in the Ydirection when it contacts the elastic deformer 154 a of the accessoryshoe spring 154 illustrated in FIGS. 17A and 17B, and thereby the topsurface of the shoe engagement portion 300 d contacts the bottom surfaceof the engagement member 151. Thereby, the position of the externalflash unit 120 relative to the camera 100 is determined in the Ydirection.

When the contact portion 300 e of the shoe attachment leg 300 a contactsthe contact surface 152 b on the front side in the Z direction of theconnection terminal connector 152, the position of the external flashunit 120 relative to the camera 100 is determined in the Z direction.The holding member 300 is also a structure for coupling the shoeattachment legs 300 a and the base portion 250, and the lock pin 252 andthe connection terminal 257 are arranged inside the coupler 300 h.

In this embodiment, the case where the camera 100, the accessory 200,and the intermediate accessory 300 have 21 or 15 contacts has beendescribed, but the number of contacts may be other numbers.

In this embodiment, the microphone device and the strobe device havebeen described as the accessory 200, but the accessory according to thepresent invention includes various devices, such as the electronicviewfinder unit, other than the microphone device and the strobe device.This embodiment has described the camera as an electronic apparatus, butthe electronic apparatus according to the present invention alsoincludes various electronic apparatuses other than the camera.

OTHER EMBODIMENTS

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. An electronic apparatus detachably attached to anaccessory via an accessory shoe, the electronic apparatus comprising aplurality of contacts electrically connectable to the accessory via theaccessory shoe and arranged in a row, wherein the plurality of contactsinclude: a first signal contact used to transmit a data signal in acommunication between the electronic apparatus and the accessory; asecond signal contact used to transmit a clock signal in synchronizationwith the data signal in the communication; and a third signal contactused to receive a communication request signal from the accessory,wherein the first signal contact and the second signal contact arearranged next to each other, wherein the third signal contact isdisposed on an opposite side of the second signal contact with respectto the first signal contact, and wherein a transmission of the datasignal via the first signal contact is executed in response to areception of the communication request signal via the third signalcontact.
 2. The electronic apparatus according to claim 1, whereinduring the communication via the first signal contact, no communicationis performed except for the clock signal to the accessory via the secondsignal contact and the communication request signal from the accessoryvia the third signal contact.
 3. The electronic apparatus according toclaim 1, wherein an open drain communication is executed via the firstsignal contact and the second signal contact.
 4. The electronicapparatus according to claim 1, wherein an open drain communication isexecuted via the third signal contact.
 5. The electronic apparatusaccording to claim 1, wherein the first signal contact and the secondsignal contact are signal contacts used for an I2C communication.
 6. Theelectronic apparatus according to claim 1, comprising a fourth signalcontact used to transmit a control signal for controlling a lightemission of an illumination unit from the electronic apparatus on anopposite side of the first signal contact with respect to the secondsignal contact, wherein the control signal is transmitted before orafter the communication via the first signal contact and the secondsignal contact.
 7. The electronic apparatus according to claim 1,comprising, on an opposite side of the first signal contact with respectto the third signal contact, a fifth signal contact, a sixth signalcontact, a seventh signal contact, and an eighth signal contact in thisorder, wherein in response to the communication request transmitted tothe accessory via the fifth signal contact, at least one of a receptionof the data signal via the sixth signal contact and a transmission ofthe data signal via the seventh signal contact is executed insynchronization with the clock signal transmitted to the accessory viathe eighth signal contact.
 8. The electronic apparatus according toclaim 7, wherein the communication of the data signal via the sixthsignal contact and the seventh signal contact is faster than thecommunication of the data signal via the first signal contact.
 9. Theelectronic apparatus according to claim 7, wherein an open draincommunication is executed via the first signal contact, and wherein acommunication by a CMOS output is executed via the sixth signal contactand the seventh signal contact.
 10. The electronic apparatus accordingto claim 1, further comprising a communication controller configured tocontrol the communication with the accessory.
 11. The electronicapparatus according to claim 1, wherein the electronic apparatus is animage pickup apparatus.
 12. An accessory detachably attached to anelectronic apparatus via an accessory shoe, the accessory comprising aplurality of contacts electrically connectable to the accessory shoe ofthe electronic apparatus and arranged in a row, wherein the plurality ofcontacts include: a first signal contact used to transmit a data signalin a communication between the electronic apparatus and the accessory; asecond signal contact used to receive a clock signal in synchronizationwith the data signal in the communication; and a third signal contactused to transmit a communication request signal to the electronicapparatus, wherein the first signal contact and the second signalcontact are arranged next to each other, wherein the third signalcontact is disposed on an opposite side of the second signal contactwith respect to the first signal contact, and wherein a reception of thedata signal via the first signal contact is executed in response to atransmission of the communication request signal via the third signalcontact.
 13. The accessory according to claim 12, wherein during thecommunication via the first signal contact, no communication isperformed except for the clock signal from the electronic apparatus viathe second signal contact and the communication request signal to theelectronic apparatus via the third signal contact.
 14. The accessoryaccording to claim 12, wherein an open drain communication is executedvia the first signal contact and the second signal contact.
 15. Theaccessory according to claim 12, wherein an open drain communication isexecuted via the third signal contact.
 16. The accessory according toclaim 12, wherein the first signal contact and the second signal contactare signal contacts used for an I2C communication.
 17. The accessoryaccording to claim 12, comprising a fourth signal contact used toreceive a control signal for controlling a light emission of anillumination unit from the electronic apparatus on an opposite side ofthe first signal contact with respect to the second signal contact, andwherein the control signal is received before or after the communicationvia the first signal contact and the second signal contact.
 18. Theaccessory according to claim 12, comprising, on an opposite side of thefirst signal contact with respect to the third signal contact, a fifthsignal contact, a sixth signal contact, a seventh signal contact, and aneighth signal contact in this order, wherein in response to thecommunication request received from the electronic apparatus via thefifth signal contact, at least one of a transmission of the data signalvia the sixth signal contact and a reception of the data signal via theseventh signal contact is executed in synchronization with the clocksignal received from the electronic apparatus via the eighth signalcontact.
 19. The accessory according to claim 18, wherein thecommunication of the data signal via the sixth signal contact and theseventh signal contact is faster than the communication of the datasignal via the first signal contact.
 20. The accessory according toclaim 18, wherein an open drain communication is executed via the firstsignal contact, and wherein a communication by a CMOS output is executedvia the sixth signal contact and the seventh signal contact.
 21. Theaccessory according to claim 12, wherein the plurality of contacts arearranged in a first direction orthogonal to an attachment direction ofthe accessory to the electronic apparatus, wherein the accessorycomprises a connector having a protrusion that protrudes in a directionof attaching to the electronic apparatus and a direction orthogonal tothe first direction at a position on both outer sides of the pluralityof contacts in the first direction, wherein the plurality of contactsinclude a reference potential contact connected to a reference potentialon at least one of both ends, and wherein the protrusion includes aslope portion on a side not facing the plurality of contacts so that awidth in the first direction of a tip in a protruding direction issmaller than that at a position away from the tip.
 22. The accessoryaccording to claim 12, comprising a communication controller configuredto control the communication with the electronic apparatus.
 23. Theaccessory according to claim 12, wherein the electronic apparatus is animage pickup apparatus.